Intermountain West Climate Dashboard

The Intermountain West Climate Dashboard is intended to replace some features of the Intermountain West Climate Summary by serving climate graphics that are automatically updated as often as the original providers post them on their respective websites (the update frequency is listed under each graphic). We are also posting text briefings once or twice per month, based on the climate graphics. Note: the text in the latest briefing may not be fully consistent with the climate graphics in the Dashboard, depending on the weather and updates in the graphics since that briefing was posted.

Click on any graphic to view a full-sized version, and click again to reduce it. You can enlarge multiple graphics at the same time, and click-drag to move them around your desktop.

The name of each graphic below is linked to the page for that graphic at the provider's website.

See this page for detailed descriptions of all of the Dashboard graphics, or click the above each graphic to see the description of that graphic.

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Skip down to the briefings (Latest briefing: July 11)

 

Recent Temperatures and Precipitation, and Current Snowpack
30-day Temp. Anomaly
(HPRCC)

30-day Temperature Anomaly

(updated daily)

30-day Precip as % Avg
(HPRCC)

30-day Precipitation Anomaly

(updated daily)

 

Drought Monitoring
US Drought Monitor
(NDMC)

US Drought Monitor(updated weekly)

State Drought Monitors (NDMC) 3-month Standardized Precip Index (SPI)
(HPRCC)

Western US Seasonal Precipitation(updated daily)

12-month Standardized Precip Index (SPI)
(HPRCC)

Western US Seasonal Precipitation(updated daily)

CO Drought MonitorColorado
UT Drought MonitorUtah
WY Drought MonitorWyoming
Current Streamflow, Forecasted Streamflow
Current Streamflow - CO
(USGS)

Colorado Current Streamflow

(updated daily)

Current Streamflow - UT
(USGS)
Utah Current Streamflow(updated daily)
Current Streamflow - WY
(USGS)

Wyoming Current Streamflow

(updated daily)

Western US Snowpack Anomaly
(updated monthly, Jan-May only)


Reservoir Storage, Seasonal Climate Outlooks
Upper Colorado Reservoir Storage
(Bureau of Reclamation)
Reservoir Storage: Upper Colorado River Basin
(updated daily)

Wasatch Front Reservoir Storage
(Reclamation)

Reservoir Storage Map: Wasatch Front(updated daily)

Monthly & Seasonal Climate Outlooks
(NOAA CPC)
1-month precip forecast, 0.5-mo lead

1-month precip, 0-mo lead

3-month precip, 0.5-mo lead

3-month precip, 1.5-mo-lead

1-month temp, 0-mo lead

3-month temp, 0.5-mo lead

3-month temp, 1.5-mo lead

Precipitation and Snow Forecasts, Drought Outlook
5-Day Quant. Precip Forecast
(NOAA HPC)
5-day Quant Precip Forecast(updated daily)
Experimental Seasonal Precipitation Forecast Guidance
Seasonal Drought Outlook
(NOAA CPC)
Seasonal Drought Forecast
(updated twice-monthly)
ENSO Conditions & Forecasts
ENSO Prediction Plume (forecasts of Nino 3.4 SST)
(IRI)

ENSO Prediction Plume

Multivariate ENSO Index

(updated monthly)

Latest Monthly Briefing - July 11, 2014

 

Highlights

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

June Precipitation and Temperatures, and Current Drought

June was much drier than average across most of the region Western US Seasonal Precipitation. Western Colorado, south-central Wyoming, and all of Utah except for the Wasatch region received less than 50% of average precipitation, with southern Utah and far southwestern Colorado seeing virtually no precipitation. Only northern Wyoming, southwestern Wyoming, and northeastern Colorado were wetter than average for the month.

Even in the driest parts of the region, June temperatures remained close to average Western US Seasonal Precipitation, with most of Utah and southern Colorado 0-2°F warmer than the monthly average, and Wyoming and northern Colorado 0-4°F to cooler than average.

The latest US Drought Monitor US Drought Monitor, shows slightly more drought across the region compared to early June. Drought conditions improved further in eastern Colorado but worsened in south-central Colorado. Abnormally dry conditions emerged in southwestern Wyoming. The proportion of the region in D2 or worse drought: Utah unchanged at 22%, Colorado unchanged at 17%, and Wyoming unchanged at zero.

Spring-Summer Runoff and Current Streamflows

With the meltout of snowpacks nearly complete, streamflows across the region are quickly declining from their seasonal peaks. No further snowmelt flooding has occurred since early June. As of July 9, the maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Mapshow that flows are generally normal to much above normal in Colorado and Wyoming, and mainly below normal or normal in Utah. On July 9, Colorado River near Cameo, CO was in the 70th percentile, 139% of median flow; the Green River near Greendale, UT was in the 56th percentile, 105% of median flow; and the San Juan River near Bluff, UT, was only in the 25th percentile, 44% of median flow.

Reservoir Storage

With the above-average runoff in Wyoming and most of Colorado, storage has rebounded in most of the region’s reservoirs after dry years in 2012 and 2013. At the end of June, nearly all major reservoirs in Colorado tracked by NRCS had more storage than at this time last year, and a majority were above the long-term average, especially in the Upper Colorado and South Platte basins. In Wyoming, nearly all major reservoirs had both more storage than last year and more than the long-term average for end of June. In Utah, however, with a drier-than-average runoff season only about half of the major reservoirs had more storage than last year, and less than one-quarter had more than the long-term average for end of June.

As of July 9, Lake Powell held 12.70 MAF (52% full) Reservoir Storage: Upper Colorado River Basin, up by more than 1 MAF from storage on the same date last year (11.60 MAF; 47% full). Powell storage now appears to be close to its annual peak for 2014.

Seasonal Climate and Drought Forecasts, including ENSO

The monthly Climate Outlook for July released on June 30 by NOAA CPC 1-month precip forecast, 0.5-mo lead shows a wet tilt for precipitation for nearly all of Utah, Wyoming, and Colorado, with the strongest tilt in eastern Utah, western Colorado, and southern Wyoming. The seasonal outlooks released June 19 also show a wet tilt in precipitation for our entire region for the July–September 3-mo precip forecast, 0.5-mo lead and August–October 3-mo precip forecast, 0.5-mo lead periods, with the strongest tilt in eastern Utah, western Colorado, and southern Wyoming in the earlier period, and in the southern two-thirds of Utah and nearly all of Colorado for the later period. The relatively wet CPC outlooks reflect the expectation of an active monsoon season.

The latest CPC Seasonal Drought Outlook released June 19 Stream Gauge Map projects that the areas of drought conditions (D1 or worse) across Colorado and Utah will improve or be removed by the end of September. No additional areas of drought development in the region are expected.

The experimental PSD precipitation forecast guidance ('SWcast'), released June 17 for the July–September periodExperimental Seasonal Precipitation Forecast Guidance has a much drier outlook than the CPC forecasts, calling for a dry tilt over most of Utah and Colorado, with the strongest dry tilt in eastern Colorado. The difference from the CPC outlooks stems from the statistical SWcast model keying off different indicators of climate system behavior than the dynamical model that is driving the CPC outlooks.

Over the last month, the ramp-up of atmospheric and oceanic conditions towards an El Niño event has slowed somewhat, but the forecasts are still calling for an event to emerge in the next several months. The Multivariate ENSO Index (MEI) dropped slightly in the May-June time frame compared to April–May Multivariate ENSO Index, but is still in El Niño territory. In the IRI ENSO Prediction Plume from mid-June ENSO Prediction Plume, about 80% of the models are calling for El Niño onset by the fall period (September–November). If the El Niño develops, the forecasts indicate that it is more likely to be a weak or moderate event than a strong event.

 

 

Previous Briefings

 

June 13, 2014

 

Highlights

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

May Precipitation and Temperatures, and Current Drought

May was wetter than average across Colorado (except the southeastern quarter), southern Utah, and far southeastern Wyoming Western US Seasonal Precipitation. The month was drier than average in northern Utah and nearly all of Wyoming, though only relatively small areas saw less than 50% of average precipitation.

May temperatures Western US Seasonal Precipitation were up 3°F to cooler than average in most of Colorado, eastern Utah, and eastern Wyoming, and up to 4°F warmer than the monthly average, in the remainder of Wyoming and Utah.

The latest US Drought Monitor US Drought Monitor, representing conditions as of June 10, shows slightly less drought for the region compared to early May. Drought conditions improved in eastern and southwestern Colorado, while worsening in a smaller area of south-central Colorado. The proportion of the region in D2 or worse drought: Utah unchanged at 22%, Colorado at 17%, down from 19%, and Wyoming unchanged at zero.

Current Snowpack

Early June is typically well past the peak accumulation at even the highest-elevation SNOTEL sites, and many sites have normally melted out by this date. Thus, the numerical percent-of-median-SWE values on the Current Basin Snowpack Map Western US Seasonal Precipitation should be treated with caution. That said, the prevalence of dark blue colors (>150% of median) on the map in Colorado, Wyoming, and far northern Utah does indicate an unusually large and persistent late-season snowpack in those basins. The basins in southwestern Colorado and southern Utah that were lagging behind seasonal normals throughout the spring have completely melted out and are not shown on the map.

According to the Colorado Dust-on-Snow Program (CODOS), no more dust events have occurred since May 13, leaving the seasonal total at eight events. The latest CODOS update noted that consolidated dust layers from events D3–D8 were exposed at the snow surface during field surveys done from June 2–4 at CODOS sites at Grand Mesa, Hoosier Pass, Loveland Pass (Grizzly Peak), Berthoud Pass, Willow Creek Pass, Rabbit Ears Pass, and McClure Pass, as well as Independence Pass. With the exposed dust, snow-surface albedo (reflectivity) is unusually low, and melt rates will be above-average through the remainder of the season, leading to a steeper-than-average declining limb of the annual hydrograph. 

 

Spring Runoff and Current Streamflows

Overall, observed runoff in April and May has been consistent with the May 1 water supply forecasts made by the NOAA Colorado Basin River Forecast Center and by the NRCS. Runoff has been above-average to much-above average in most of Wyoming, and northern and central Colorado. Below to much-below-average runoff has been observed in southwestern and south-central Colorado, southwestern Utah, and most of the eastern Great Basin.

As is typical for early June, mountain snowpacks have been melting rapidly, and rivers in the basins that accumulated above-normal snowpacks have produced high daily flows. Many gages in northern and central Colorado saw record-high or near-record daily flows in late May or early June. The Colorado River near Dotsero peaked slightly above flood stage, while on the other side of the Continental Divide, the Cache la Poudre River peaked well above flood stage west of Fort Collins and in Greeley, causing damage to several dozen homes and businesses. Flows at these gages, and elsewhere in northern and central Colorado, are now probably past the seasonal peak but remain much above normal. Most parts of the Front Range impacted by flooding last September have been spared further flooding so far.

As of June 12, the maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Map show that flows are normal to much above normal in Colorado and Wyoming, and mainly below normal or normal in Utah.

Reservoir Storage

After two years of below-average runoff depleted the region’s water storage, this spring's runoff thus far has helped most of the region's reservoirs regain lost ground. At the end of May, nearly all reservoirs in Colorado and Wyoming had more storage than last year, while Utah's reservoirs are more split between gains and losses compared to last year. As of June 11, Lake Powell held 11.76 MAF (48% full) Reservoir Storage: Upper Colorado River Basin, down very slightly from 11.79 MAF (48% full) on the same date last year. However, last year at this time Powell's storage had nearly peaked for the season, while now Powell is still gaining about 80,000 AF per day, and should continue to gain storage through June.

Spring–Summer Streamflow Forecasts

The June 1 forecasts issued by NCRS and NOAA CBRFC for spring–summer streamflow across the region are generally similar to the May 1 forecasts, except in the Colorado Headwaters, Yampa-White, and South Platte basins in Colorado, where above-average May precipitation led to considerable increases in the runoff forecasted for June and July. Note that NRCS does not update their Westwide Streamflow Forecast Map, shown above in the Dashboard, past May 1.

IMPORTANT NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC. The NRCS June 1 forecast for Lake Powell April–July inflows is 7300 KAF, 102% of average, up from 7160 KAF in the May 1 forecast. The NOAA CBRFC June 1 forecast for Lake Powell inflows is 7550 KAF, 105% of average, which is unchanged from the May 1 forecast.

Seasonal Climate and Drought Forecasts, including ENSO

The monthly Climate Outlook for June released on May 31 by NOAA CPC 1-month precip forecast, 0.5-mo lead shows a wet tilt for precipitation for nearly all of Wyoming, and northern and eastern Colorado, with the strongest tilt in far eastern Wyoming. The seasonal outlooks released May 15 show a wet tilt in precipitation for our entire region for the June–August 3-mo precip forecast, 0.5-mo lead and July–September 3-mo precip forecast, 0.5-mo lead periods, with the strongest tilt in eastern Utah, western Colorado, and southwestern Wyoming.

The latest CPC Seasonal Drought Outlook released May 15 Stream Gauge Map projects that the areas of drought conditions (D1 or worse) in Colorado and southeastern Utah will improve or be removed by the end of August, while drought areas in western Utah will persist through that time frame. No additional areas of drought development are expected.

As reported in the previous briefing, according to the experimental PSD precipitation forecast guidance ('SWcast'), for the April–June period Experimental Seasonal Precipitation Forecast Guidance there is a dry tilt for southern Utah, extending into northwestern Colorado, and a slight wet tilt for southwestern Colorado. For the July–September periodExperimental Seasonal Precipitation Forecast Guidance there is a dry tilt for all of Utah, and northern and eastern Colorado. Note that forecast skill is relatively poor for the latter period and lead time.

Atmospheric and oceanic conditions continue to indicate that an El Niño event is emerging. The Multivariate ENSO Index (MEI) experienced its 2nd largest increase ever for the April–May timeframe Multivariate ENSO Index, moving sharply into El Niño territory. In the IRI ENSO Prediction Plume from mid-May ENSO Prediction Plume, nearly all of the models call for continued near-term warming in the Niño 3.4 region. By the late-summer period (July–August), a little under two-thirds of the models are calling for El Niño onset, reaching over 70% by fall. The consensus of the forecasters is that El Niño onset is even more lilkely than indicated by the models. Assuming the El Niño develops, it is still very uncertain how strong it may become.

 

 

May 13, 2014

 

Highlights

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

April Precipitation and Temperatures, and Current Drought

After a wet late winter and early spring for the region’s mountains, April brought below-average precipitation to most mountain areas, with the exception of northwestern Wyoming Western US Seasonal Precipitation. Utah was on the dry side except for the far northern and the far eastern portions of the state. In Colorado, there were wet pockets in the south-central and northeast, with the rest of the state seeing below-average to average precipitation. Wyoming was mostly drier than average, especially the southwestern quarter of the state. The second week of May brought a couple of potent systems that dropped 0.5"–3” of precipitation across the region, providing a big boost to the snowpack, with north-central Colorado and southeast Wyoming seeing the highest totals.

April temperatures were close to normal across the region, with few areas more than 2°F above or below the monthly average Western US Seasonal Precipitation.

The latest US Drought Monitor, representing conditions as of May 6 US Drought Monitor, shows a net increase in drought severity in our region since early April. Drought conditions worsened in southeastern Utah and adjacent southwestern Colorado, and in eastern Colorado. Improvement was seen in southeastern Wyoming. The proportion of the region in D2 or worse drought increased again, with Utah up to 22% from 16%, Colorado up to 19% from 15%, and Wyoming unchanged at zero.

Current Snowpack

May 13 is past the typical peak snow accumulation date for all basins in our region and all but the highest-elevation and northernmost sites. The percent-of -median-SWE values may be misleading in those basins that are well down the declining limb of their seasonal snowpack trajectory, such as in southern Utah.

A generally dry April was balanced out by a wet early May in most mountain areas, so the Current Basin Snowpack map from NRCS Western US Seasonal Precipitation shows that conditions as of May 13 are similar to where they were one month ago. Wyoming and northern Colorado continue to have above-normal to much-above-normal SWE, with nearly all basins at 130% of median SWE or greater. Northern Utah basins are near or above normal, while the remainder of the state is below-normal and headed to early meltout, albeit delayed by the most recent storms. In Colorado, the San Juan-San Miguel-Dolores (75% of median SWE) and Rio Grande (56% of median SWE) basins are lagging well behind the rest of the state.

According to the Colorado Dust-on-Snow Program, three dust-on-snow events affected at least southwestern Colorado in late April and early May, bringing the seasonal total to eight, one more than the average number of seasonal events since 2005. Consolidation and surface exposure of the previous dust layers from the larger events D3, D4, and D5 led to earlier and faster snowmelt throughout April in many parts of the Colorado mountains, especially in the San Juans. While these dust layers have now been reburied by the most recent snows, they will re-emerge in coming days to weeks and continue to hasten snowmelt and runoff.

Current Streamflows

The maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Map show that flows are near normal to above normal in Colorado and Wyoming, with several gages in Wyoming reporting daily record high flows. Flows are mainly normal to much below normal in Utah, with a few gages recording record daily low flows.

Spring-Summer Streamflow Forecasts

The Westwide Streamflow Forecast Map based on the NRCS May 1 forecasts Western US Snowpack Anomaly shows small decreases from the April 1 forecasts in several basins, including southeastern and central Wyoming and central Utah. Most forecast points in Wyoming and northern and central Colorado are expected to have near-average (90-109%), above-average (110–129%) or much-above-average (130–149%) spring and summer runoff. Most forecast points in south-central and southwestern Colorado, and most forecast points across Utah, are expected to have below-average (70–89%) to much-below-average (50-69%) spring and summer runoff, with an increasing number of points expected to have far-below-average (25–49%) runoff, and four southern Utah points in the under-25% category. Most points in northern Utah and west-central Colorado are expected to have below-average (70-89%) to near-average (90–109%) runoff.

In the watersheds in the northern Front Range of Colorado (St. Vrain/Boulder, Big Thompson, upper Cache la Poudre) that were most affected by the floods last September, SNOTEL sites are still showing much-above-normal (>130% of median) SWE. The NRCS May 1 forecasts for these basins slipped slightly, to 107–122% of average spring–summer runoff, though these forecasts were made prior to the snow accumulation from the major storm on May 10–13. According to NOAA NWS, there is still a high potential for snowmelt flooding in these basins. Since stream channels are impacted by debris and excess sediment in many locations in these basins, the risk and severity of flooding may be greater than in previous high-runoff years.

IMPORTANT NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC. The NRCS May 1 forecast for Lake Powell April–July inflows is 7160 KAF, 100% of average. The NOAA CBRFC May 1 forecast for Lake Powell inflows is 7550 KAF, which is 105% of average.

Seasonal Climate and Drought Forecasts

The monthly Climate Outlook for April released on April 30th by NOAA CPC shows a wet tilt for precipitation for nearly all of Wyoming, and far northeastern Colorado, with the strongest tilt in northern Wyoming1-month precip forecast, 0.5-mo lead. The seasonal outlooks released April 17 show a wet tilt in precipitation for most of Utah and Colorado for May–July 3-mo precip forecast, 0.5-mo lead and June–August 3-mo precip forecast, 0.5-mo lead periods, with the strongest tilt in eastern Utah and western Colorado. The latest CPC Seasonal Drought Outlook released April 17 Stream Gauge Map projects that the areas of drought conditions (D1 or worse) in Utah and Colorado will persist through at least July, but no additional areas of drought development are expected.

According to the experimental PSD precipitation forecast guidance ('SWcast'), for the April–June period Experimental Seasonal Precipitation Forecast Guidance there is a dry tilt for southern Utah, extending into northwestern Colorado, and a slight wet tilt for southwestern Colorado. For the July–September periodExperimental Seasonal Precipitation Forecast Guidance ere is a dry tilt for all of Utah and northern and eastern Colorado. Note that forecast skill is relatively poor for the latter period and lead time.

The prospect of an El Niño event emerging in the next several months looks increasingly likely, with atmospheric and oceanic conditions indicating a continued progression towards El Niño. In the IRI ENSO Prediction Plume from mid-April ENSO Prediction Plume , all of the models call for near-term warming in the Niño 3.4 region, and by the mid-summer period (June–August), two-thirds of the models are calling for El Niño onset, exceeding 75% by the September–November period. The experimental PSD ENSO forecast has a >80% chance of El Niño development by mid-summer. Assuming the El Niño develops, there is still great uncertainty as to how strong it may become.

 

April 9, 2014


Highlight

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

March Precipitation and Temperatures, and Current Drought

As during much of this winter, the storm tracks and dynamics in March favored the northern portions of our region, especially the mountains. Areas with above-average to much-above-average precipitation for the month included most of Wyoming, northwestern and north-central Colorado, far northern Utah, and small areas of southern Utah and southern Colorado Western US Seasonal Precipitation. The remainder of southern Utah, southwestern Colorado, and eastern Colorado were much drier than average. The first week of April saw systems that brought above-average precipitation to most of Colorado, northern and central Utah, and western Wyoming.

The pattern in temperature anomalies across the region in March Western US Seasonal Precipitation reflected the continued incursions of cold air masses into the north-central and midwestern US, with northern Wyoming and central and east-central Colorado ending the month colder than average by 0–6°F. Outside of the influence of these cold waves, Utah, southern Wyoming, and the rest of Colorado were 0–6°F warmer than average.

The latest US Drought Monitor, representing conditions as of April 1 US Drought Monitor, shows a net increase in drought severity in our region since early March. Improvement was seen in south-central and southeastern Wyoming (from D0 to drought-free). But drought conditions worsened in southwestern Utah (D0 to D1, and D1 to D2), southeastern Utah and adjacent southwestern Colorado (D0 to D1), and southeastern Colorado (D2 to D3). The proportion of the region in D2 or worse drought increased slightly, with Utah bumped up to 16% from 11%, Colorado nudged up to 15% from 14%, and Wyoming unchanged at zero.

Current Snowpack
The Current Basin Snowpack map from NRCS Western US Seasonal Precipitation shows little change since early March, with most of the region having near- to much-above-normal SWE as of April 8. Wyoming, northern Colorado, and far northern Utah are at 120% of median SWE or greater, with over 140% of median SWE in western, north-central, and southeastern Wyoming, and northeastern Colorado. Conditions in central and south-central Utah have improved slightly since March 1, with SWE now at 70–105% of median. Southwestern and southeastern Utah basins have continued to see dry conditions, and have experienced early snowmelt, and snowpacks are well below normal at 50–55% of median. Southwestern and south-central Colorado are also lagging behind the basins to the north, at around 85% of median. Early April typically represents the peak snowpack accumulation in many basins.

According to the Colorado Dust-on-Snow Program, there were four dust-on-snow events that affected at least southwestern Colorado in February and March, and a fifth on April 1. Two of the five WY2014 events, both in late March (D3 and D4), deposited substantial amounts of dust. Both events extended to central and northern Colorado, though only D4 left a prominent dust layer in those areas. Since 2005, the number of seasonal dust-on-snow events by April 1 has ranged from one to seven, with an average of four events. The month of April has the highest occurrence of dust events, with an average of three events since 2005.

Current Streamflows

The maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Map show that the majority of gages are now free of ice and reporting. Flows are mainly near normal or above normal in Wyoming and Colorado, while they are mainly normal to below normal in Utah.

Spring-Summer Streamflow Forecasts

The Westwide Streamflow Forecast Map based on the NRCS April 1 forecasts Western US Snowpack Anomalyshows little change from March 1st, with most forecast points in Wyoming and northern and central Colorado expected to have above-average (110–129%) or much-above-average (130–149%) spring and summer runoff. Most forecast points in south-central and southwestern Colorado, and most forecast points across Utah, are expected to have below-average (70–89%) to much-below-average (50-69%) spring and summer runoff, with a handful of points expected to have far-below-average (25–49%) runoff, and three southern Utah points in the under-25% category. Many points in northern Utah and west-central Colorado are expected to have near-average (90–109%) runoff.

The watersheds in the northern Front Range of Colorado (St. Vrain/Boulder, Big Thompson, upper Cache la Poudre) that were most affected by the floods last September have unusually large snowpacks for early April, at around 150% of median SWE. The NRCS April 1 forecasts for these basins call for 125–130% of average spring–summer runoff. According to NOAA NWS, there is a high potential for snowmelt flooding in these basins. Since stream channels are impacted by debris and excess sediment in many locations in these basins, the risk and severity of flooding may be greater than in previous high-runoff years. Multiple state and federal agencies are cooperating to remove debris and sediment from these channels in preparation for high runoff.

IMPORTANT NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC. The NRCS April 1 forecast for Lake Powell April–July inflows is 7900 KAF, 110% of average. The NOAA CBRFC April 1 forecast for Lake Powell inflows is 7850 KAF, which is also 110% of average.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlook released on March 31st by NOAA CPC shows a dry tilt for precipitation for far southwestern Utah for April 1-month precip forecast, 0.5-mo lead. The seasonal outlooks released March 20 show no tilt in precipitation, and so equal chances for wet or dry conditions, for our region for the AprilJune 3-mo precip forecast, 0.5-mo lead and May–July 3-mo precip forecast, 0.5-mo lead periods. The latest CPC Seasonal Drought Outlook released March 20 Stream Gauge Map projects that the areas of drought conditions (D1 or worse) in Utah and southern Colorado will persist through at least June, but no additional areas of drought development are expected.

ENSO indicators such as the Niño 3.4 anomaly that are updated daily (not shown on the Dashboard) have been rapidly shifting from cool-side-of-neutral conditions into warmer territory since mid-March. This was anticipated by the consensus of the IRI ENSO Prediction Plume ENSO Prediction Plume for mid-March, in which nearly all of the models called for near-term warming in the Niño 3.4 region. By the mid-summer period (June–August), over half of the models forecast El Niño onset, reaching 60% by the September–November period. Last month, NOAA CPC hoisted an El Niño Watch, indicating that “conditions are favorable for the development of El Niño conditions within the next six months.” An experimental PSD regression-based MEI forecast issued March 10 projects a still higher likelihood of El Niño development, at 64% probability for the July–September period. Based on the intensity of recent tropical wind forcing, subsurface ocean heat anomalies, and historical comparisons, the likelihood of a substantial El Niño event in 2014 has greatly increased over the last two months.

 

March 14, 2014


Highlight

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

February Precipitation and Temperatures, and Current Drought

As in January, precipitation in February was unevenly distributed across our region, with the storm tracks and dynamics generally favoring the high mountains as well as some adjacent areas to the east of the mountains. Areas with above-average to much-above-average precipitation included western and north-central Wyoming, southeastern Wyoming and portions of eastern Colorado, and the high mountains in Colorado and northern and central Utah Western US Seasonal Precipitation. Central and south-central Wyoming, most of the lower-elevation areas of Colorado, and southern and northeastern Utah were drier than average. Overall, an active and consistent weather pattern persisted through the month and into early March, with repeated shots of Pacific moisture in the same locations with each passing low-pressure trough.

There was a striking pattern in temperature anomalies across the region in February Western US Seasonal Precipitation. East of the Continental Divide in Wyoming and Colorado saw temperatures colder than average by 3–12°F, as repeated Arctic cold waves sloshed into those areas. West of the Divide, including all of Utah, temperatures were 3–9°F warmer than average. Worland, in central Wyoming, was 11.5°F below normal for the month, while about 300 miles away, Salt Lake City was 7.9°F above normal for the month, an almost 20-degree differential in the anomaly.

The latest US Drought Monitor, representing conditions as of March 11 US Drought Monitor, shows improvement since early February in areas of central and northeastern Colorado (from D0 to drought-free), central and northern Wyoming (from D1 to D0, and D2 to D1) and northern Utah (D2 to D1). The proportion of the region in D2 or worse drought changed little, with Utah nudged down from 13% to 11%, Colorado remaining at 14%, and Wyoming unchanged at zero.

Current Snowpack
The Current Basin Snowpack map from NRCS Western US Seasonal Precipitation shows most of the region with near- to much-above-normal SWE. With the storm tracks since January favoring Wyoming and northern Colorado, those areas have about 120% of median SWE or greater, with over 140% of median SWE in western, north-central, and southeastern Wyoming, and northeastern Colorado. Conditions in northern Utah have improved considerably since February 1, with SWE now at 100–120% of median. Central and southern Utah, especially in the southwestern corner, have been drier and warmer the past two months and snowpacks are below-median (45–90%) and some have even started early melt. Southwestern and south-central Colorado are also lagging behind the basins to the north, at around 90% of median.

Current Streamflows

The maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Map show that the majority of Wyoming gages are ice-affected and have no data, while in Utah and Colorado many gages are now reporting. Of the gages that are reporting, flows are mainly normal or above normal Wyoming and Colorado, while they are mainly normal or below normal in Utah.

Spring-Summer Streamflow Forecasts

The Westwide Streamflow Forecast Map based on the NRCS March 1 forecasts Western US Snowpack Anomalyshows that most forecast points in Wyoming and northern and central Colorado are expected to have above-average (110–129%) or much-above-average (130–149%) spring and summer runoff.  Most forecast points in south-central and southwestern Colorado, and much of Utah, are expected to have below-average (70–89%) to much-below-average (50-69%) spring and summer runoff, with a handful of points expected to have far-below-average (25–49%) runoff, and two points in the under-25% category. Many points in northern Utah and west-central Colorado are expected to have near-average (90–109%) runoff.

The watersheds in the northern Front Range of Colorado that were most affected by the floods last September now have unusually large snowpacks, generally over 150% of median SWE for early March and above the 90th percentile. The NRCS March 1 forecasts for these basins call for above-average (110–129%) seasonal runoff. According to NOAA NWS, there is a high risk of minor snowmelt flooding in these basins. Since stream channels are impacted by debris and excess sediment in many locations in these basins, the risk and severity of flooding may be greater than in previous high-runoff years. Multiple state and federal agencies are cooperating to remove debris and sediment from these channels in preparation for high runoff.

IMPORTANT NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC. For example, the NRCS March 1 forecast for Lake Powell April–July inflows is 7800 KAF, 109% of average. The NOAA CBRFC March 1 forecast for Lake Powell inflows is 8300 KAF, 116% of average.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlook released on February 28th by NOAA CPC shows only a slight wet tilt in precipitation for far southern Utah and Colorado for March 1-month precip forecast, 0.5-mo lead. The seasonal outlooks released February 20 show no tilt in precipitation for our region for the March–May 3-mo precip forecast, 0.5-mo lead and April–June 3-mo precip forecast, 0.5-mo lead periods. The latest CPC Seasonal Drought Outlook released February 20 Stream Gauge Mapprojects that the areas of drought conditions (D1 or worse) in our region, in Utah and southeastern Colorado, will persist through at least May, but no additional drought development is expected.

As reported in the previous briefing, the PSD experimental April 1 SWE forecast for Colorado released in mid-January has the median (50th percentile) forecast Experimental Colorado SWE Forecast Guidance calling for near or above-average April 1 snowpack (92–110% of average) for all basins, with the highest forecasted SWE in the Arkansas and Yampa-White basins, and the lowest SWE in the San Juan-San Miguel-Dolores and Rio Grande basins.

In the ENSO arena, we finally have a real prospect of change. While ENSO indicators are still showing ENSO-neutral conditionsENSO Nino 3.4 Time-series Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) , the forecast models are increasingly pointing towards development of El Niño conditions. The IRI ENSO Prediction Plume ENSO Prediction Plume for mid-February shows that starting in the mid-summer period (June–August) just under half of the models call for El Niño onset, with about half remaining in neutral territory. The early March update of NOAA CPC/IRI’s probabilistic forecast shows marginally higher likelihoods of El Niño development by summer, at or just above 50%.

Accordingly, NOAA CPC has hoisted an El Niño Watch, indicating that “conditions are favorable for the development of El Niño conditions within the next six months.” An experimental PSD regression-based MEI forecast issued March 10 projects a higher likelihood of El Niño development, at 64% probability for the July–September period.


February 14, 2014

 

Highlights

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

January and early February Precipitation and Temperatures, and Current Drought

Precipitation in January was very unevenly distributed across our region, with storm tracks generally favoring the northern areas. The northern two-thirds of Colorado and much of northern and central Wyoming ended up wetter than average, while south-central and southwest Wyoming, southern Colorado, and nearly all of Utah were drier than average Western US Seasonal Precipitation. Even drier conditions occurred just to the south, as New Mexico and Arizona received virtually no precipitation for the month.

An active weather pattern at the end of January continued in early February. From February 7–10 a deep flow of Pacific moisture from an atmospheric river (AR) event penetrated unusually far to the east, bringing at least 2” of moisture to most high mountain areas in northern and central Utah, Wyoming, and Colorado. Northern Utah and northwestern Colorado were especially favored by this event, with up to 8” of SWE accumulating in the northern Wasatch Range and 7” in the Park Range near Steamboat Springs. A second, more northerly, AR event was affecting northwestern Wyoming, northern Utah, and northern Colorado as of February 13.

Temperatures across the region in January were less exceptional than in December Western US Seasonal Precipitation . Most of the region was warmer than average, especially in southern Utah and southwestern Wyoming. Portions of northern and central Colorado, central Wyoming, and northern Utah were colder than average.

The latest US Drought Monitor, representing conditions as of February 11 US Drought Monitor, shows improvement since early January in areas of northwestern Colorado (from D0 to drought-free) and in northern Utah (from D1 to D0, and D2 to D1) and south-central and western Wyoming (D0 to drought-free) D1 to D0. Conversely, areas in southwestern and northeastern Colorado degraded from drought-free to D0. The proportion of the region in D2 or worse drought changed little, with Utah nudged down from 14% to 13%, Colorado remaining at 14%, and Wyoming unchanged at zero.

Snowpack
The Current Basin Snowpack map from NRCS Western US Seasonal Precipitation shows that conditions have improved significantly for most of the region in the past two weeks. The most recent storms favored the north, while leaving southern Utah, and portions of southwestern Colorado with little or no new snow. As of February 13, SWE is near-normal or above-normal (>90% of median) in every Wyoming basin, all of Colorado except the Rio Grande, and south-central and northern Utah, with the best conditions (>135% of median SWE) in north-central and northeastern Wyoming, and north-central Colorado. Snowpacks are below normal to much below normal in southwestern and southeastern Utah, with the driest basins at around 60% of median SWE.

Current Streamflows
The maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Mapshow that the majority of gages are ice-affected and have no data, which is typical for this time of year. Among the gages still reporting, no clear tendencies are apparent.

Spring-Summer Streamflow Forecasts
The February 1 spring-summer streamflow forecasts were released by NOAA CBRFC and the NRCS in early February. Note that the heavy snow accumulation in many basins in early February is not reflected in the forecasts, and there may be large improvements in the March 1 forecasts, relative to the February 1 forecasts. The CBRFC’s ESP (Ensemble Streamflow Prediction) forecasts are updated daily and can be accessed here.

The Westwide Streamflow Forecast Map based on the NRCS February 1 forecasts Western US Snowpack Anomaly shows that most forecast points in northern and central Colorado, and northern and eastern Wyoming are expected to have near-average (90–109%) or above-average (110–129%) spring and summer runoff.  Most forecast points in south-central and southwestern Colorado, southwestern Wyoming, and Utah are expected to have below-average (70–89%) to much-below-average (50-69%) spring and summer runoff, with a handful of points expected to have far-below-average (25–49%) runoff.

IMPORTANT NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC. For example, the NRCS February 1 forecast for Lake Powell April–July inflows is 6700 KAF, 94% of average. The NOAA CBRFC February 1 forecast for Lake Powell inflows is 7250 KAF, 101% of average.

Seasonal Climate and Drought Forecasts
The latest monthly Climate Outlook released on January 31st by NOAA CPC shows no tilt in precipitation for our regiong for January 1-month precip forecast, 0.5-mo lead. The seasonal outlooks released January 16 shows a tilt towards drier conditions, strongest in the Southwest, progressively edging into southern Utah and southern Colorado in the February–April 3-mo precip forecast, 0.5-mo leadand March–May periods 3-mo precip forecast, 0.5-mo lead. The latest CPC Seasonal Drought Outlook released January 16 Stream Gauge Map projects that the areas of drought conditions (D1 or worse) in our region, mainly in Utah, will persist through at least April, with additional areas of drought developing in southeastern Utah and southern Colorado.

The new PSD Precipitation Forecast Guidance ("SWcast") released January 17 for January–March 2014 Experimental Seasonal Precipitation Forecast Guidance shows a dry tilt over much of northern and central Colorado, with the strongest dry tilt (-10%) over north-central Colorado. A wet tilt is shown over southern Utah and southwestern Colorado.

The PSD experimental April 1 SWE forecast for Colorado released in mid-January has the median (50th percentile) forecast Experimental Colorado SWE Forecast Guidance calling for near or above-average April 1 snowpack (92–110% of average) for all basins, with the highest forecasted SWE in the Arkansas and Yampa-White basins, and the lowest SWE in the San Juan-San Miguel-Dolores and Rio Grande basins.

ENSO indicators Stream Gauge Map Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) are yet again showing ENSO-neutral conditions, with Niño 3.4 right at the zero-anomaly line and the MEI slightly below zero. IRI has not updated their ENSO Prediction Plume since mid-December, so the current forecasts are not displayed in the Dashboard. But this February 6 update from NOAA CPC addresses the current forecasts: “Nearly all model forecasts indicate the persistence of ENSO-neutral [conditions] through the Northern Hemisphere spring 2014, but afterwards, an increasing number of models suggest the possible onset of El Niño.”

 

January 10, 2014

 

Highlights

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

December Precipitation and Temperatures, and Current Drought

Over much of the region, most of December’s precipitation fell in the first week, associated with the strong cold wave. Storm tracks generally stayed to the north for the rest of the month. Most of Wyoming, western Utah, far northeastern Utah, and central Colorado ended the month wetter than average, while the rest of Utah, and southern and eastern Colorado were drier than average Western US Seasonal Precipitation.

Temperatures in December were colder than average across nearly all of the region Western US Seasonal Precipitation. Utah and western Colorado experienced the largest and most widespread cold anomalies, with most locations more than 6°F below normal and parts of northeastern Utah more than 15°F below normal. These monthly anomalies were driven by a very strong cold wave during the first week of December. Denver experienced below-zero low temperatures for six days in a row, the longest such stretch in December since 1972. Grand Junction was 13°F below normal for the month, including 10 days with below-zero temperatures, compared to the long-term average of 1 below-zero day in December. Early January conditions have been near or above average over most of the region.

The latest US Drought Monitor, representing conditions as of January 7 US Drought Monitor, shows improvement since early December in areas of central Utah (from D2 to D1) and eastern Utah (D1 to D0). Also, north-central Wyoming improved (from D0 to drought-free) due to above-average December and early fall precipitation. Drought conditions worsened in portions of east-central Colorado (D0 to D1) and southeastern Colorado (D1 to D2). The proportion of the region in D2 or worse drought saw little change, with Utah at 14% (down by 2%), Colorado at 14% (up by 2%), and Wyoming at zero (no change).

Snowpack
The Current Basin Snowpack map from NRCS Western US Seasonal Precipitation indicates that conditions have deteriorated in many basins due to below-average snowfall since early December. As of January 9, basins have near-normal or above-normal SWE (>90% of median) across nearly all of Wyoming, most of Colorado, and in south-central Utah, with the best conditions (>130% of median SWE) in north-central and northeastern Wyoming. Snowpacks are below normal to much below normal in the rest of Utah, southwestern Wyoming, and southwestern Colorado, with the driest basins at or just below 70% of median SWE. A storm coming in January 9th-12th should boost snowpacks in the northwestern Wyoming, northern Utah, and northern Colorado but will not help the southern part of the region.

Current Streamflows
The maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Mapshow that the majority of gages are ice-affected and have no data, which is typical for this time of year. Among the gages still reporting, no clear tendencies are apparent. December unregulated inflows into Lake Powell were 81% of average.

Spring-Summer Streamflow Forecasts
The first spring-summer streamflow forecasts of the season, valid January 1, were released by NOAA CBRFC and the NRCS in early January. The NRCS Westwide Streamflow Forecast MapWestern US Snowpack Anomaly shows that most forecast points in northern and western Colorado, northern and eastern Wyoming, and southeastern Utah are expected to have near-average (90-109%) or above-average (110-129%) spring and summer runoff.  Most forecast points in south-central Colorado, southwestern Wyoming, and the remainder of Utah are expected to have below-average (70-89%) to much-below-average (50-69%) spring and summer runoff. 

IMPORTANT NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC. For example, the NRCS January 1 forecast for Lake Powell April-July inflows is 6500 KAF, 91% of average. The NOAA CBRFC January 1 forecast for the same point is 6810 KAF, 95% of average. Also note that the January 1 forecasts do not reflect declines in snowpack since the first of the month.

Seasonal Climate and Drought Forecasts
The latest monthly Climate Outlook released on December 31st by NOAA CPC shows a slight wet tilt for precipitation for northern Wyoming for January 1-month precip forecast, 0.5-mo lead, and a slight dry tilt for southwestern Utah. The seasonal outlooks released December 19 show a slight tilt towards drier conditions for southern Utah and central Colorado, but no tilt elsewhere in the region, for the January–March period 3-mo precip forecast, 0.5-mo lead. For the February–April period, a slight dry tilt is shown for far southern Utah and the southwestern corner of Colorado 3-mo precip forecast, 0.5-mo lead. The latest CPC Seasonal Drought Outlook released December 19 Stream Gauge Mapprojects that most of the areas of drought conditions (D1 or worse) in our region, mainly in Utah, will persist through at least March, with additional  areas of drought developing in southeastern Utah and western Colorado.

As reported in the previous briefing, the PSD Precipitation Forecast Guidance ("SWcast") released November 13 for January–March 2014 Experimental Seasonal Precipitation Forecast Guidance shows a dry tilt over nearly all of Utah and Colorado, with the strongest dry tilt (-10%) over north-central Colorado. Even so, the non-ENSO indicators in the Pacific Ocean, and in the Atlantic Ocean, are not as suggestive of drought as they were last year at this time.

ENSO indicators Stream Gauge Map Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) are yet again showing ENSO-neutral conditions, with Niño 3.4 right at the zero-anomaly line and the MEI slightly below zero. The models in IRI's mid-December ENSO Prediction Plume ENSO Prediction Plume once again indicate a consensus towards ENSO-neutral conditions continuing through the winter into spring, with both the dynamical and statistical models tending towards the warm side of neutral, and a handful of models calling for El Niño conditions by summer.

 

December 10, 2013

Highlights

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

November Precipitation and Temperatures, and Current Drought

While the storm tracks in October favored the northern part of our region, in late November a major storm took a southerly path, resulting in above-average precipitation for the month Western US Seasonal Precipitation in southeastern and west-central Utah, and in western and south-central Colorado. Nearly all of Wyoming, northern Utah, and eastern Colorado were drier than average. The mountain areas in Colorado and in southern Utah generally received above-average precipitation.  

Temperatures in November were slightly warmer than average, by 0–2°F, across most of the regionWestern US Seasonal Precipitation except for those areas with the most precipitation, which were slightly cooler. (The still-lingering severe cold wave that moved into region starting December 2–4 will be covered in the January briefing.)

The latest US Drought Monitor, representing conditions as of December 3 US Drought Monitor, shows improvement since early November in areas of southern Utah (from D1 to D0) and southwestern Colorado (D0 to drought-free) that received much-above-average precipitation in November. The proportion of the region in D2 or worse drought remained steady, with Utah at 16%, Colorado at 12%, and Wyoming at zero.

Snowpack
The Current Basin Snowpack map from NRCS Western US Seasonal Precipitation indicates above-normal SWE in nearly all basins in our region—a welcome change from early December conditions in the previous two winters. The largest positive anomalies, with over 140% of median SWE for the date, are in northern Wyoming, southern Utah, and the southern half of Colorado, reflecting the very wet October in Wyoming, the wet November in the southern mountains, and a generally wet start to December. Snowpacks are below normal in several basins in northern and central Utah and far southwestern Wyoming, but no basin has less than 80% of median SWE as of December 9.

Current Streamflows

The maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Mapshow an increasing number of ice-affected gages with no data, and other data may be unreliable as the cold wave of early December is affecting lower-elevation gages unusually early. The Colorado River near Cisco, UT gage was just beginning to freeze up on December 6, with flows in the 44th percentile (96% of median flow).

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlook released on November 30 by NOAA CPC shows a wet tilt for precipitation for Wyoming for December 1-month precip forecast, 0.5-mo lead, but no tilt elsewhere. The seasonal outlooks released November 21 show a slight tilt towards wetter conditions for most of Wyoming, but no tilt elsewhere in the region, for the December–February period 3-mo precip forecast, 0.5-mo lead. For the January–March period, a slight dry tilt is shown for southern Utah and Colorado 3-mo precip forecast, 0.5-mo lead. The latest CPC Seasonal Drought Outlook released November 21 Stream Gauge Map projects that most of the areas of drought conditions (D1 or worse) in our region, mainly in Utah, will persist through at least February, except for improvement along Utah’s Wasatch Front and in east-central Wyoming.

The PSD Precipitation Forecast Guidance ("SWcast") released November 13 for January–March 2014 Experimental Seasonal Precipitation Forecast Guidance shows a dry tilt over nearly all of Utah and Colorado, with the strongest dry tilt (-10%) over north-central Colorado. Even so, the non-ENSO indicators in the Pacific Ocean, and in the Atlantic Ocean, are not as suggestive of drought as they were last year at this time.

The experimental January 1 SWE forecast for Colorado released in early October has the median (50th percentile) forecast SWcast Experimental Precipitation Forecast Guidance calling for above-average January 1 snowpack (109–117% of average) for all basins except the Yampa (93%) and Rio Grande (98%).

ENSO indicators Stream Gauge Map Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) are still showing ENSO-neutral conditions, though with a warming trend over the past few months.The models in IRI's mid-November ENSO Prediction Plume Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri)once again indicate a consensus towards ENSO-neutral conditions continuing through the winter, though both the dynamical and statistical models are tending towards the warm side of neutral, with several models calling for El Niño conditions by spring.


November 11, 2013

 

Highlights

 

October Precipitation and Temperatures, and Current Drought

In October, storm tracks favored the Northern Plains and left nearly all of Wyoming with above-normal precipitationWestern US Seasonal Precipitation; much of the state was over 200% of normal. To the south, this wet anomaly extended into northern Colorado and far western Colorado, and a portion of eastern Utah. The rest of Colorado and Utah saw drier-than-normal conditions, including persistently drought-stricken southeastern Colorado.

After the relatively dry conditions during the first 10 days of November, the current HPRCC Water Year Precipitation map for 2014Western US Seasonal Precipitation shows essentially the same pattern as for the month of October.

October’s temperatures were cooler than average across the region—and across the entire western US—even in those areas with below-average precipitationWestern US Seasonal Precipitation. Most areas were 2–6°F below average monthly temperatures for October, which helped keep the new snow in the mountains on the ground.

The latest US Drought Monitor, representing conditions as of November 5 Modeled Soil Saturation Index, shows further improvement in the persistent drought conditions over the past month. The most significant improvements were in southern and eastern Wyoming, where D2 and D3 drought conditions on October 1 improved to D0 and D1. Lesser improvements occurred in south-central and northwestern Colorado. The proportion of Wyoming in D2 or worse drought dropped to zero, from 22% on October 1; Utah remained at 16%; and Colorado remained at 12%. Region-wide, the overall drought extent and severity is now lower than it has been since early 2012.

Snowpack
The Current Basin Snowpack map from NRCS Western US Seasonal Precipitation indicates near- to above-average SWE in all but a handful of basins in our region, with the largest positive anomalies in Wyoming, southern Utah, and northwestern Colorado. We are still very early in the snowpack season, and the % of average SWE values are more volatile than later in the season. With average to dry conditions forecasted for the region for the next 5 5-day Quant Precip Forecast to 14 days, these values may slip backwards by late November, especially in Utah and much of Colorado where the actual SWE amounts on the ground are generally less than 2".

Current Streamflows

The maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Map show that streams in the region are generally in lower flow categories than one month ago, but most are still in the normal or above-normal categories. The Colorado River near the CO-UT state line was in the 40th percentile (96% of median flow) on November 9.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlook released on October 31 by NOAA CPC shows a slight dry tilt for precipitation for November 1-month precip forecast, 0.5-mo lead extending into extreme southern Colorado, but no tilt elsewhere. The seasonal outlooks released October 17 show a tilt towards wetter conditions for most of Wyoming, but no tilt elsewhere in the region, for the November–January period 3-mo precip forecast, 0.5-mo lead, and no tilt for the December–February period 3-mo precip forecast, 0.5-mo lead. The latest CPC Seasonal Drought Outlook released October 17 projects that the remaining areas of drought conditions (D1 or worse) in our region, mainly in Utah, will persist through at least January Stream Gauge Map.

As reported in the October 8 briefing, the PSD Precipitation Forecast Guidance ("SWcast") released September 11 for October–December 2013 conditions shows a slight wet tilt for the period for far northeastern Colorado, and a dry tilt for most of eastern Colorado into the northern Front Range. No tilt is forecasted for the rest of Colorado and Utah, indicating equal chances for wet, dry, and middle outcomes. The fall-early winter period historically has shown the least forecast skill of all seasons, though there has been positive skill east of the Continental Divide.

Also reported in the October 8 briefing: in the experimental January 1 SWE forecast for Colorado released in early October, the median (50th percentile) forecast SWcast Experimental Precipitation Forecast Guidance calls for above-average January 1 snowpack (109–117% of average) for all basins except the Yampa (93%) and Rio Grande (98%).

ENSO indicators Stream Gauge MapMap of real-time streamflow compared to historical streamflow for the day of the year (Missouri) are still showing ENSO-neutral conditions, though with a warming trend over the past few months. The models in IRI's mid-October ENSO Prediction Plume Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) once again indicate a consensus towards ENSO-neutral conditions continuing through the winter, though now both the dynamical and statistical models are tending towards the warm side of neutral, with a few models sneaking into El Niño territory by spring.

 

October 8, 2013

 

Highlights

 
Click on the thumbnail images in the text below to bring up the full-sized graphic

September Precipitation and Temperatures, and Current Drought

September ended the 2013 water year on a very wet note across the region, with most of the region receiving at least 200% of normal precipitation, and only a few small areas seeing drier-than-normal conditions Western US Seasonal Precipitation. The last month with comparable wet anomalies across the region was December 2007. A persistent rain event from September 9th–17th,  caused by a late monsoonal surge from the south reinforced in eastern Colorado by very moist upslope flow, brought most of the month's precipitation, including extraordinary totals for Boulder, Colorado (9" in 24 hours; 17” in seven days) and the surrounding area.  (See the WWA’s preliminary assessment of the Front Range rain event and the severe flooding it caused.)

Other areas with over 5” of precipitation for the month included far southeastern Wyoming, south-central Utah, the Uinta Basin in northeastern Utah, the southeastern Yellowstone Plateau, and the San Juans in southwestern Colorado.

With this late surge, the final HPRCC Water Year Precipitation map Western US Seasonal Precipitation for 2013 showed that the previously scattered areas with above-average precipitation since October 1 have enlarged and merged, covering perhaps one-third of the three-state region, with the wettest areas in northeastern Colorado, southern Utah, and northern Wyoming. But, as in the 2012 water year, most of the region still ended up drier than normal.

Despite all the precipitation, the temperatures in SeptemberWestern US Seasonal Precipitation were warmer than average across the region, except in parts of western Utah and western Colorado. Most areas were 1–6°F above monthly average temperatures for September.

The latest US Drought Monitor, representing conditions as of October 1 Modeled Soil Saturation Index, shows significant and widespread improvement in the persistent drought conditions, by one to three categories, compared to one month ago. The most dramatic improvements were in northeastern Colorado, where up to D2 drought conditions were brought to normal, and in southwestern Colorado, where D3 drought improved to D0 Modeled Soil Saturation Index. The proportion of Colorado in D2 or worse drought dropped from 60% on September 3 down to 12% on October 1; in Utah, 54% down to 16%; and in Wyoming, 48% to 22%. Region-wide, the overall drought extent and severity is now lower than it has been since April 2012.

Current Streamflows

As with the other hydroclimatic indicators, the maps of current streamflows for Colorado Map of flood and high flow condition (Missouri), Utah Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri), and Wyoming Stream Gauge Map clearly show the effect of the prodigious September precipitation. In Colorado and Wyoming, there are many gages in the much above normal (dark blue) and high (black) categories, and relatively few in the below-normal categories. Utah has a more equitable distribution across the flow categories. The Colorado River near the CO-UT state Line was in the 64th percentile (118% of median flow) on October 5.

Aided by very high flows on the San Juan River, Lake Powell received inflows of 0.86 MAF in September, over 200% of the average inflows for September, and over twice the combined inflows in July and August this year. As a result, the final water year inflows to Powell should come in closer to 5.0 MAF (47% of average), versus the 4.3 MAF projected at the beginning of September.

Reservoir Storage

The well-above-average precipitation in many parts of the region provided an unexpected but welcome boost to reservoirs at a time of year they are typically dropping towards their winter-early spring low stands. In the flooding-affected drainages of Colorado’s Front Range, several small to mid-size (<50 KAF) reservoirs filled and spilled, while large reservoirs in western Colorado saw well-above-average inflows and gains in storage, including Dillon, Blue Mesa and Navajo Reservoirs.

On September 30, Lake Powell held 10.93 MAF (45% full), up from the 10.79 MAF held on August 31, and more significantly, well above the 10.5 MAF (43% full) projected in early September as the end-of-water-year contents. The surface elevation of Powell on September 30 was 5 feet higher than had been projected three weeks earlier.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlook released on September 30 by NOAA CPC show a dry tilt for precipitation for October 1-month precip forecast, 0.5-mo lead covering all of Colorado and Utah, and southern Wyoming. The seasonal outlooks released September 19 show a slight tilt towards wetter conditions in far northern Wyoming, but no tilt elsewhere in the region, for the October–December period 3-mo precip forecast, 0.5-mo lead, and a slight wet tilt in northern Wyoming and a slight dry tilt for southern Colorado and Utah for the November–January period 3-mo precip forecast, 0.5-mo lead. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons South Platte Time Series South Platte Time Series, consistent with long-term warming trends. The latest CPC Seasonal Drought Outlook released September 19 projects that drought conditions over most of our region, though much improved last month, will persist through at least December, with no additional improvement expected.

The PSD Precipitation Forecast Guidance ("SWcast") released September 11 for October–December 2013 conditions SWcast Experimental Precipitation Forecast Guidance shows a slight wet tilt for the period for far northeastern Colorado, and a dry tilt for most of eastern Colorado into the northern Front Range. No tilt is forecasted for the rest of Colorado and Utah, indicating equal chances for wet, dry, and middle outcomes. The fall-early winter period historically has shown the least forecast skill of all seasons, though there has been positive skill east of the Continental Divide.

Klaus Wolter of NOAA PSD has also issued the first experimental January 1 SWE forecast for Colorado, with separate forecasts for the seven state water divisions, which follow the major river basins. The median (50th percentile) SWcast Experimental Precipitation Forecast Guidance forecast calls for above-average January 1 snowpack (109–117% of average) for all basins except the Yampa (93%) and Rio Grande (98%).

Stop us if you've heard this one before: ENSO indicators Stream Gauge Mapcontinue to show ENSO-neutral conditions, as they have for the past 12 months. The models in IRI's mid-September ENSO Prediction Plume Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) again indicate a consensus towards ENSO-neutral conditions continuing through the fall and early winter, with the dynamical models tending towards the warm side of neutral, and the statistical models tending to stay on the cool side.

 

September 5, 2013

 

Highlights

 

Click on the thumbnail images in the text below to bring up the full-sized graphic

August Precipitation and Temperatures, and Current Drought

Throughout August, the monsoon continued to bring subtropical moisture into the region, but the results were more spotty than in July. Much of Colorado, southern Utah, and far northeastern Wyoming were wetter than average, but northern Utah and the rest of Wyoming were drier than averageWestern US Seasonal Precipitation. The southern Front Range including Colorado Springs saw 5–8" of rainfall for the month, with some locations seeing about half of their annual average. Conversely, parts of far northern Utah and central and northern Wyoming had less than 25% of average precipitation, and these same areas were also very dry in July. With one month left in the water year, the HPRCC Water Year Precipitation map Western US Seasonal Precipitation still shows only isolated parts of the region with above-average precipitation since October 1.

As in July, the temperatures in AugustWestern US Seasonal Precipitationwere warmer than average across most of the region, except in parts of southern Utah and western Colorado. Most areas were 1–4°F above monthly average temperatures for August. Salt Lake City was again the hot spot, capping off its hottest summer (June–August) ever with a record-hot August 2013 which averaged 82.7°F (5.7°F above average).

Many of the areas that were wetter-than-average during August have improved by one or two categories in the latest US Drought Monitor Modeled Soil Saturation Indexrepresenting conditions as of September 3. The largest areas of improvement are in northeastern Colorado (to D1) and southeastern Colorado (to D2/D3)Modeled Soil Saturation Index. In Wyoming there were smaller areas of improvement in the northeastern and southeastern corners, while D1 expanded slightly in the northwestern corner. In Utah, there was an expansion of D2 in the northwestern part of the state. Overall, drought conditions across the region are similar to where they were at the beginning of June, with improvement in Colorado balanced by drying in Utah and Wyoming.

Current Streamflows

The maps of current streamflows across Colorado Map of flood and high flow condition (Missouri) and UtahMap of real-time streamflow compared to historical streamflow for the day of the year (Missouri), show more gages in the "normal" (green) and above-normal categories, compared to one month ago. In Wyoming, however, there has been no improvement since early August, and below-normal gages still outnumber the normal and above-normal gages. The Colorado River near the CO-UT state Line was in the 41st percentile (95% of median flow) on September 4, very similar to early August.

The Bureau of Reclamation's latest forecast for unregulated water-year 2013 inflows to Lake Powell is 4.3 MAF (40% of average). This would make 2000-2013 the driest 14-year period on record, averaging 8.2 MAF compared to the 1981–2010 mean of 10.8 MAF.

Reservoir Storage

At this time of year, the region's reservoirs are typically slipping towards their winter-early spring low stands. On August 31, Lake Powell Reservoir Storage: Upper Colorado River Basinheld 10.79 MAF (44% full), down from 14.15 MAF (58% full) on the same day last year.

According to Reclamation's 24-Month Study Report released August 16, the level of Lake Powell is forecasted to fall just below 3575' by January 1, 2014', which, in combination with Lake Mead being above 1025', triggers the Mid-Elevation Release Tier, in which 7.48 MAF would be released from Powell in water year 2014. This would likely be the first release of less than 8 MAF since Lake Powell first filled in the early 1980s.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks released on August 31 by NOAA CPC show a slight wet tilt for precipitation for September1-month precip forecast, 0.5-mo lead covering most of Utah and the western two-thirds of Colorado. The seasonal outlooks released August show a tilt towards wetter conditions in far northern Wyoming, but no tilt elsewhere in the region, for the and September–November and October–December periods 3-mo precip forecast, 0.5-mo lead 3-mo precip forecast, 0.5-mo lead. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons South Platte Time Series South Platte Time Series , consistent with long-term warming trends. The latest CPC Seasonal Drought Outlook Stream Gauge Mapreleased August 15 projects that drought conditions will persist for most of our region through November, but further improvement is expected in south-central Coloradoup through the Front Range over the next three months.

As reported in the previous briefing: The PSD Precipitation Forecast Guidance ("SWcast") released July 12 for July–September 2013 conditions, shows a wet tilt for the period for eastern Colorado, and a stronger dry tilt for the northern Front Range SWcast Experimental Precipitation Forecast Guidance, similar to the previous forecast for this period issued in May. Both of the regions showing tilt have shown modest positive forecast skill for the late-summer/early fall over the last decade. No tilt is forecasted for the rest of Colorado and Utah, indicating equal chances for wet, dry, and middle outcomes.

ENSO indicators Stream Gauge Map Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) continue to show ENSO-neutral conditions, as they have since last fall. The models in IRI's mid-August ENSO Prediction Plume Map of real-time streamflow compared to historical streamflow for the day of the year (Missouri) again indicate a consensus towards ENSO-neutral conditions continuing through the fall and early winter, with the dynamical models tending towards the warm side of neutral, and the statistical models tending to stay on the cool side. The model envelope suggests some chance of weak El Niño or La Niña conditions developing this winter.

 

August 7, 2013

 

Highlights

 

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July Precipitation and Temperatures, and Current Drought

July was a rare month for this water year: the majority of the region experienced above-average precipitation, as a timely and active monsoon consistently brought subtropical moisture into the region. Conditions were generally wetter across Utah and Colorado than Wyoming, with the largest wet anomalies in southwestern Utah and far western Colorado. Conversely, extreme north-central Utah, far northwestern Colorado, and parts of southwestern Wyoming were mostly skipped by the July rains. We are far enough along in the water year that one good month scarcely changed the HPRCC Water Year Precipitation map, which still shows only isolated areas with above-average precipitation since October 1.

Despite the moisture, July temperatures were warmer than average across most of the region, except in parts of eastern Colorado and far northeastern Wyoming. Most areas were 0-4°F above monthly average temperatures for July. The hot spot for the region was Salt Lake City, where July 2013 clocked in at an average of 84.1°F (5.4°F above average), the warmest July and warmest month since the official record began in 1928, just beating out July 2007.

After the July rains, the latest US Drought Monitor representing conditions as of July 30, shows multiple small areas of improvement by one category: along the Colorado Front Range (to D0), along the Wasatch Front (to D0), in southwestern Utah (to D0), far northeastern Colorado (to D1 and D2), and southeastern Colorado (to D3). There was also some expansion of D3 in south-central Wyoming, and east-central Colorado. Last year there was considerable expansion of drought area during July—which did not occur this year—so overall conditions are now somewhat better than at this time last year.

Current Streamflows

Once again, in the maps of current streamflows across Colorado, Utah, and Wyoming, there are more gages in the below-normal categories than the above-normal categories, but more gages are in the "normal" (green) category than one month ago. The July rains have had a positive effect on streamflows in many Colorado and Utah basins. For example, the Colorado River near the CO-UT state Line jumped from from the 8th percentile on July 1 to the 46th percentile (95% of median flow) on August 4. This gain was not just relative to the median; streamflows actually increased from about 3000 cfs to 3600 cfs over this period.

However, this boost in July streamflows has been “too little, too late”, and has not substantially increased the overall low to very low April–July runoff across the region, especially in the Upper Colorado River Basin. The preliminary observed unregulated inflows to Lake Powell for April through July totaled 2.55 MAF (39% of median), well below the "most probable" June 1 forecast of 3.0 MAF. This was the 4th lowest spring-summer runoff since 1964, below 1981 but above 2012.

Reservoir Storage

After a second straight year of generally poor April–July inflows, the region’s reservoirs tended to reach their seasonal peak levels "early and low" this year. As of July 31, the vast majority of reservoirs were below the long-term average for the date, and generally below last year's level as well. On July 31, Lake Powell held 11.20 MAF (46% full), down from 14.68 MAF (60% full) on the same day last year.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks released on July 31 by NOAA CPC show a wet tilt for precipitation for August in far northern Wyoming, but no tilt elsewhere. The seasonal outlooks released July 18 show no tilt towards wetter or drier conditions for the August–October and September–November periods. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with long-term warming trends. The latest CPC Seasonal Drought Outlook released July 18 projects that drought conditions will persist for most of our region through October, but further improvement is expected in southeastern Utah and southwestern and south-central Colorado over the next three months, reflecting the expected continuation of what has been a robust monsoon so far.

The latest PSD Precipitation Forecast Guidance ("SWcast") released July 12 for July–September 2013 conditions, shows a wet tilt for the period for eastern Colorado, and a stronger dry tilt for the northern Front Range, similar to the previous forecast for this period issued in May. Both of the regions showing tilt have shown modest positive forecast skill for the late-summer/early fall over the last decade. No tilt is forecasted for the rest of Colorado and Utah, indicating equal chances for wet, dry, and middle outcomes.

ENSO indicators still continue to show ENSO-neutral conditions, as they have since last fall. The models in IRI's mid-July ENSO Prediction Plume again indicate a consensus towards ENSO-neutral conditions continuing through the fall, with the dynamical models tending towards the warm side of neutral, and the statistical models tending to stay on the cool side. Several models call for a quick cooling into La Niña conditions by fall, but most of those do not continue the La Niña event through the winter. A few dynamical models forecast the development of weak El Niño conditions by late winter.

July 2, 2013 (updated July 9)

 

Highlights

 

Note: Special WWA-NIDIS drought briefing available

On June 26, WWA and the National Integrated Drought Information System (NIDIS) released a two-page Summer 2013 Drought Summary and Outlook for Colorado, Utah, Wyoming, and New Mexico. This briefing summarizes recent precipitation, current and expected drought conditions, spring-summer streamflows, reservoir levels, agricultural impacts, and wildfire risk.

 

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June Precipitation and Temperatures, and Current Drought

June brought little relief for our drought-stricken region, with only northeastern Wyoming and portions of southeastern Colorado seeing above-average precipitation. Most of Utah, far western Colorado, and parts of southwestern Wyoming received virtually no precipitation. The HPRCC Water Year Precipitation mapstill shows only isolated areas with above-average precipitation since October 1.

June temperatures were warmer than average across the region, with most areas being 2-6°F above monthly average temperatures.

The latest US Drought Monitor, representing conditions as of July 2, shows an expansion of D3 (extreme) drought conditions since early June in the Four Corners region, extreme south-central Utah, and far northeastern Colorado. An area of abnormally dry (D0) conditions along Colorado's Front Range has deteriorated to D1 (moderate drought). The region on the whole is experiencing a similar proportion of severe (D2) or worse drought compared to early July 2012, though with a different spatial pattern than last year.

Current Streamflows

In the maps of current streamflows across the three states, there are many more gages in the below-normal categories than the above-normal categories. The runoff peak has passed at all gages, and western Colorado in particular has seen many gages drop categories in the last month. For example, the Colorado River near the CO-UT State Line dropped from the 15th percentile on June 7, to the 8th percentile (36% of median flow) on July 1.

The observed volumes this spring and early summer have been on track with the dry outlook of the official forecasts. With the low June precipitation, the observed unregulated inflows to Lake Powell are running below the "most probable" forecast of 3.0 MAF for the April–July period, and will likely end up closer to 2.7 MAF for the period, which would make it the 5th lowest spring runoff on record, just below 1981 but above 2012.

Reservoir Storage

The second year of below-average runoff has further depleted the region’s water storage. At the end of June, most reservoirs across the region had less storage than last year, and the vast majority were below the long-term average for the date. There was some recovery of reservoir storage in the Upper Colorado headwaters and the adjacent portion of the South Platte basin with near-average runoff there, but storage decreases were predominant in other basins, including the North Platte, Arkansas, Rio Grande, San Juan, Green, and the Wasatch Front basins. On June 30, Lake Powell held 11.76 MAF (48% full), down from 15.29 MAF (63% full) last year.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks released on June 30 by NOAA CPC show a wet tilt for precipitation for July in far southern Utah and Colorado, reflecting the expectation for an active Southwest monsoon. The seasonal outlooks released June 20 show a tilt towards drier-than-average conditions for the July–September and August–October periods only for far northwestern Wyoming, and no tilt for the rest of the region. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with the long-term warming trend. The latest CPC Seasonal Drought Outlook released June 20 projects that drought conditions will persist for most of our region, but some improvement is expected in far southern Utah and extreme southwestern Colorado over the next three months, again reflecting the monsoon.

ENSO indicators continue to show ENSO-neutral conditions. Since last fall, ENSO conditions have not exerted much influence on the climate system, nor on the seasonal forecasts. The models in IRI's mid-June ENSO Prediction Plume again indicate a consensus towards ENSO-neutral conditions continuing through the fall, with the dynamical models tending towards the warm side of neutral, and the statistical models tending to stay on the cool side, with a few models calling for development of La Niña conditions by the end of summer.

 

June 10, 2013

 

Highlights

Click on the thumbnail images in the text below to bring up the full-sized graphic

May Precipitation and Temperatures, and Current Drought

As in April, May brought variable precipitation for the region, with central Colorado, far northern Wyoming, and portions of eastern Utah seeing well above-average precipitation. Northern Utah, southeastern Wyoming, and southern and eastern Colorado saw below-average precipitation. The HPRCC Water Year Precipitation map shows a handful of areas with above-average water-year precipitation, but most of the region has experienced drier-than-normal conditions since October 1.

May temperatures were very close to average across the region, with nearly all areas departing less than 2°F from monthly average temperatures. Wyoming overall was slightly warmer than average, and Utah and Colorado were split between warmer- and cooler-than-average conditions.

The latest US Drought Monitor, representing conditions as of June 4, shows some amelioration in drought conditions since late April in north-central Colorado, northern Utah, and northern Wyoming. An area of severe (D2) drought in southwestern Colorado and extreme southeastern Utah has deteriorated to D3 (extreme). Overall, the percentage of each state classified in severe (D2) or worse drought has decreased, with Colorado still highest at 71%, and Utah and Wyoming both at 47%. Colorado remains the only state in the region with D4 (exceptional) drought, occupying much of the southeastern quadrant of the state. Despite the recent improvement, however, the region on the whole is experiencing worse drought conditions than in early June 2012.

Current Snowpack and Streamflows

By early June, the vast majority of SNOTEL sites across the region have melted out, and this year is no exception. Thus the % of normal SWE values, as seen in the the Current Basin Snowpack map from NRCS, need to be treated with extreme caution. That said, the map broadly conveys the state of the remaining high-elevation snowpack: below-normal to near-normal conditions in northern and central Colorado, and south-central and north-central Wyoming, and much below normal or prematurely melted out elsewhere.

In the maps of current streamflows across the three states, Colorado is seeing an increased number of gages in the above-normal categories compared to a month ago, reflecting the seasonal peak runoff in those basins with near-normal snowpacks. But across all three states, there are more gages in the below-normal categories than the above-normal categories. The Colorado River near the CO-UT State Line has slipped from the 24th percentile on May 2 to the 15th percentile (52% of median flow) on June 7, reflecting overall below-normal snowpacks in the Colorado headwaters and the Gunnison basins.

Spring-Summer Streamflow Forecasts

The June 1 spring-summer streamflow forecasts from NOAA and the NRCS have deteriorated compared with May 1 for most basins across the region, except for the Colorado headwaters and upper Gunnison basin, which saw above-normal May precipitation. The NRCS Westwide Streamflow Forecast Map shows that the vast majority of basins are forecasted to have well-below-average (50–69%) or lower runoff. For Lake Powell inflows, the official CBRFC forecast for June 1 is at 3.0 MAF (42% of average), unchanged from the May 1 forecast.

Note that these April–July runoff forecasts issued on June 1 include two months of observed streamflow (April and May). The observed volumes this spring have been consistent with the dry outlooks of the previous months' forecasts; across the Upper Colorado River Basin, for example, observed streamflows for May ranged from 40–85% of average.

(NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC.)

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks released on May 31 by NOAA CPC show a dry tilt for precipitation for June in northern Utah, western Wyoming, and southeastern Colorado. The seasonal outlooks released May 16 show a tilt towards drier-than-average conditions for the June–August period for southeastern Colorado, but no tilt for the rest of the region. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with the long-term warming trend. The latest CPC Seasonal Drought Outlook released June 6 projects that drought conditions will persist for most of our region, but some improvement is expected in eastern Wyoming and northeastern Colorado over the next three months.

As reported in the previous briefing, the SWcast released April 15 for late summer (July–September) has a slight dry tilt for northwestern Utah, and also for extreme north-central Colorado and southern Wyoming, with a slight wet tilt for eastern Colorado.

ENSO indicators continue to show ENSO-neutral conditions. Since last fall, ENSO conditions have not exerted much influence on the climate system, nor on the seasonal forecasts. The models in IRI's mid-May ENSO Prediction Plume indicate a consensus towards ENSO-neutral conditions continuing through next summer and fall, with the dynamical models tending towards the warm side of neutral, and the statistical models tending to stay on the cool side, with a few models calling for development of weak La Niña conditions by the end of summer.

 

May 6, 2013 (updated May 7)


Highlights

April Precipitation and Temperatures, and Current Drought

April brought a mixed bag of precipitation for the region , with storms consistently favoring northern and central Colorado, portions of Wyoming, and eastern Utah, with some areas seeing over 200% of normal precipitation. Conversely, northern Utah, southwestern Wyoming, and southern Colorado were mostly skipped by these storms and saw below-average precipitation. The HPRCC Water Year Precipitation map shows that the wetter areas in April have emerged as the largest "green islands" of above-average water-year precipitation, in a sea of drier-than-normal conditions since October 1. Southeastern Colorado remains by far the driest part of the region over that period, with isolated pockets in southern Colorado and in Utah also seeing less than 50% of average October–April precipitation.

Several severe cold-air outbreaks led to April temperatures being colder than average across the region , except for parts of southeastern Utah and southwestern Colorado. Dozens of daily record-low minimum temperatures were set during April throughout the region, including 2°F in Boulder, CO on April 10, and -7°F in Cody, WY on April 9, which was also a monthly record for April.

The latest US Drought Monitor, representing conditions as of April 30, shows further improvement in regional drought conditions since late March; extreme (D3) drought in central western Colorado and central Wyoming has been upgraded to D2 and D1. While majority of the region is still classified in severe (D2) or worse drought, relatively little is now in D3 and D4, with the largest and most persistent area of D4 occupying most of southeastern Colorado.

Current Snowpack and Streamflows

As reported in the previous briefing, a series of storms after April 8 significantly boosted snowpacks in many mountain areas, with the last storm sweeping in on April 30. This late in the season, the % of normal SWE values, as seen in the the Current Basin Snowpack map from NRCS, can be misleading since nearly all SNOTEL sites have typically begun to melt out by now. But it is fair to say that the basins in northern and central Colorado, northeastern Utah, and much of Wyoming clawed their way back to near-normal (90–100%) snowpack conditions at the higher elevations by May 1. Snowpacks in southern Utah and southern Colorado did not seem the same boost in April as the basins to the north, and the snow there has been melting out steadily since mid-April, leaving May 1 values at 70% of normal or less, even at the highest elevations. Overall, the snowpack picture for the region is generally improved over April 1.

In Colorado, the new snow in April was accompanied by two substantial dust-on-snow events, with the storm on April 15–16 depositing dust from the San Juans to the Front Range. The dust loading in the San Juans is now similar to the high-dust springs of 2009 and 2010, and has been speeding up the snowmelt. In the northern and central mountains of Colorado, the dust layers are still buried for the most part, but once exposed will likewise cause earlier meltout than in the absence of dust. As WWA researcher Jeff Deems was quoted in the Denver Post, the April snow was "a mixed blessing" because of the dust deposition.

In the maps of current streamflows across the three states, the “normal” category is most frequently reported, but with more gages in the below-normal categories than above-normal, particularly in Wyoming. The Green River near Greendale, UT gage, was in the 12th percentile, at only 55% of the median flow for May 2, probably reflecting delayed snowmelt with the recent storms. Similarly, the Colorado River near the CO-UT State Line was in the 24th percentile, at 63% of the median flow for May 2. These flows should improve relative to normal as snowmelt picks up over the next few weeks.

Spring-Summer Streamflow Forecasts

Like the snowpacks, the May 1 spring-summer streamflow forecasts from NOAA and the NRCS are generally improved across the region compared with April 1, except in southern Colorado and southern Utah. The NRCS Westwide Streamflow Forecast Map shows a strong north-south gradient, with basins in northern Wyoming forecasted to have near-average (90–109%) or below-average (70–89%) runoff; in southern Wyoming, northern and central Colorado, and northern and eastern Wyoming, mainly below-average (70–89%) or well-below-average (50–69%) runoff; and in southern Utah and southern Colorado, far-below-average (25–49%) runoff. Only a few small basins remain in the very lowest category (<25% of average). For Lake Powell inflows, the official CBRFC forecast for May 1 is at 3.0 MAF (42% of average), slightly higher than the April 1 forecast of 2.7 MAF.

The runoff outlook for the region is lower than the final snowpack numbers (and their late-season improvement) would suggest, which reflects the unusually dry soil moisture last fall that is expected to significantly reduce runoff efficiency. (NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC.)

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks released on April 30 by NOAA CPC show a slight dry tilt for precipitation for May in northern and western Wyoming. The seasonal outlooks released April 18 show a tilt towards drier-than-average conditions for the May–July period for all of the region, with the strongest tilt over western Colorado and eastern Utah. For the June–August period, the area with dry tilt shrinks and shifts to southeastern Colorado. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with the long-term warming trend. The latest CPC Seasonal Drought Outlookreleased May 2 projects that drought conditions will persist for most of our region, but some improvement is expected in far eastern Wyoming and the eastern half of Colorado over the next three months.

The latest PSD Precipitation Forecast Guidance ("SWcast")released April 12 for April–June 2013 conditions, continues to show a wet tilt for spring and early summer for Colorado, though shifted more to eastern Colorado compared with the SWcast released in March. A modest tilt towards dry conditions is forecasted for northwestern Utah. The SWcast released April 15 for late summer (July–September) continues the slight dry tilt for northwestern Utah, and also for extreme north-central Colorado and southern Wyoming, with a slight wet tilt for eastern Colorado.

ENSO indicators continue to show ENSO-neutral conditions, on the cool (La Niña) side of neutral. Since last fall, ENSO conditions have not exerted much influence on the climate system, nor on the seasonal forecasts. The models in IRI's mid-April ENSO Prediction Plume indicate a strong consensus towards ENSO-neutral conditions continuing through next summer and fall, with the dynamical models tending towards the warm side of neutral, and the statistical models tending to stay on the cool side.

 

April 24, 2013

 

Current Snowpack

Several potent spring storms since April 8 have given the snowpacks a significant late boost in Wyoming, northern and central Utah, and northern and central Colorado, with many SNOTEL sites accumulating 2-6" of SWE over the two-week period. The Current Basin Snowpack map from NRCS shows many basins across the region now having 90–110% of median snowpack for April 23. While these values this late in the season can be misleading—the median snowpack curve has peaked and is declining at most sites after mid-April—the "current SWE as % of peak" values, especially at the highest-elevation sites, suggest that most of this recent increase in % of median is "real" and will be reflected in greater runoff than was forecasted on April 1.

The recent storms did not benefit southern Colorado and southern Utah nearly as much as farther north, and these basins remain at well below median snowpack.

Seasonal Climate and Drought Forecasts

The latest monthly and seasonal Climate Outlooks released on April 18 by NOAA CPC show no tilt for precipitation for May, but a tilt towards drier-than-average conditions for the May–July period for all of the region, with the stongest tilt over western Colorado and eastern Utah. For the June–August period. the area with dry tilt shrinks and shifts to southeastern Colorado. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with the long-term warming trend. The latest CPC Seasonal Drought Outlook released April 18 projects that over most of our region drought conditions will persist, but some improvement is expected in far eastern Wyoming and the eastern half of Colorado over the next three months.

 

April 5, 2013


Highlights

March Precipitation and Temperatures, and Current Drought

March was drier than average across the vast majority of the region, with driest conditions (>50% of average) in southern and northeastern Wyoming, southern Colorado, and northern and southeastern Utah. Only scattered areas saw above-average precipitation. The mountains across the region generally saw below-average precipitation. The HPRCC Water Year Precipitation map shows that almost the entire region has seen below-average precipitation since October 1. The largest area with <50% of average October–March precipitation is in southeastern Colorado.

March temperatures were warmer than average across most of Utah and in southwestern Colorado, and cooler than average elsewhere in the region. The largest cold anomalies, up to 6°F below average, were in northeastern Colorado and northern Wyoming.

The latest US Drought Monitor, representing conditions as of April 2, shows little change in regional drought conditions since early March. Most of the region is still classified in severe (D2) or worse drought: Colorado, 89% (unchanged since March 5); Wyoming, 84% (unchanged); and Utah, 46% (down from 52%).

Current Snowpack and Streamflows

With below-average March precipitation across nearly all mountain areas, snowpacks continued to slip with respect to normal (1981-2010 median) accumulation. April 1 SWE was well below normal across the region, with most basins between 70–85% of normal. Utah April 1 basin SWE was generally lower than on March 1, ranging from 70–90% of normal. In Colorado, April 1 basin SWE was similar to the March 1 values, at 66–82% of normal. In Wyoming, there was more variability, with the individual basin SWE ranging from 63–97% of normal. The April 1 basinwide SWE for the Upper Colorado River above Lake Powell slipped to 73% of normal, compared to 78% on March 1, and 84% on February 1.

In the maps of current streamflows across the three states, far more gages are in the below-normal categories than above-normal, particularly in Colorado. The Green River near Greendale, UT gage, was only in the 8th percentile, at 56% of the median flow for April 5. The Colorado River near the CO-UT State Line was in the 10th percentile, at 57% of the median flow for April 5.

Spring-Summer Streamflow Forecasts

The April 1 spring-summer streamflow forecasts from NOAA CBRFC and the NRCS are lower across the region than the March 1 forecasts. The NRCS Westwide Streamflow Forecast Map shows that most basins in our region are now expected to see well-below-average (50-69%) runoff or far-below-average (25-49%) runoff. Basins in northern Wyoming are in relatively better shape with forecasted below-average (70-89%) runoff. Several basins have slipped to the very lowest category (<25% of average).

For Lake Powell inflows, the official CBRFC forecast for April 1 is again lower than the previous months’, at 2.7 MAF (38% of average), compared to the March 1 forecast of 3.4 MAF. The very dry runoff outlook for the region reflects both the below-normal snowpacks and the unusually dry soil moisture last fall, which is expected to significantly reduce runoff efficiency in the spring. (NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC.)

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks for April, released on April 1 by NOAA CPC, now show no tilt for April precipitation for our region, in contrast with a dry tilt in the previous outlook, and a tilt towards warmer temperatures for April over the region, especially Utah and Colorado.

As reported in the previous briefing: The latest seasonal (3-month) Climate Outlooks released on March 21 by NOAA CPC show a tilt towards drier-than-average conditions for late spring and early summer for western Colorado and all of Utah. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with the long-term trend towards warmer conditions.

The latest CPC Seasonal Drought Outlook released April 4 projects that over most of our region drought conditions will persist, but some improvement is expected in far southeastern Wyoming and northeastern Colorado over the next three months.

ENSO indicators continue to show ENSO-neutral conditions on the cool (La Niña) side of neutral, and so we continue to see little influence of ENSO on the seasonal forecasts. The models in IRI's mid-March ENSO Prediction Plume indicate a consensus towards ENSO-neutral conditions continuing through next summer and fall.

 

March 22, 2013


Current Snowpack

The pattern seen in February with the region's snowpacks has continued since March 1, with storm tracks favoring Colorado and eastern Wyoming, where snowpacks have seen slight to moderate gains with respect to average conditions. Conversely, snowpacks in many Utah basins and in western Wyoming have slipped back. As a result, the Current Basin Snowpack map from NRCS shows nearly all basins across the region having 70–90% of average snowpack for March 22. Northwestern and north-central Wyoming have the highest basin snowpack levels, though still below average. The basinwide snowpack for the Upper Colorado River above Lake Powell as of March 22 is at 80% of average, up slightly from 78% of average on March 1. Last year at this time, the Upper Colorado River basinwide snowpack was almost identical to this year, at 81% of average. However, in 2012 the snowpack had reached a very early peak around March 20, while there is still the opportunity for further accumulation this year.

Seasonal Climate and Drought Forecasts

The latest monthly and seasonal Climate Outlooks released on March 21 by NOAA CPC continue to show a tilt towards drier-than-average conditions for late spring and early summer for western Colorado and all of Utah; this dry tilit is stronger than in the previous outlooks. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook released March 21 projects that over most of our region drought conditions will persist, but some improvement is expected in eastern Wyoming and northeastern Colorado over the next three months.

 

March 7, 2013

 

Highlights

February Precipitation and Temperatures, and Current Drought

February was drier-than-average across most of the region, with Utah overall the driest of the three states, especially in the far western and southern parts of the state. Mountain areas in northern Colorado and central and eastern Wyoming were generally favored by the prevailing storm tracks, and ended up with at least average precipitation, as did the plains adjacent to Colorado’s Front Range, and central Wyoming's basins. Mountain areas across Utah and in western Wyoming saw below-average precipitation. The HPRCC Water Year Precipitation map shows that almost the entire region has been drier than average since October 1. Southeastern Colorado remains the driest part of the region over that period, with less than 50% of average October–February precipitation.

February temperatures were colder than average across the region, except for parts of western and northeastern Wyoming. As in January, the largest cold anomalies, up to 15°F below average, were over Utah and were associated with persistent surface inversions. In northern Utah, a strong inversion caused another serious air pollution episode from February 2nd6th.

The latest US Drought Monitor, representing conditions as of March 5, shows some improvement in regional drought conditions since late January; an area of extreme (D3) drought in far western Colorado and eastern Utah was upgraded to D2, and a nearby area of D2 in southwestern Colorado and southeastern Utah was upgraded to D1. But the great majority of the region is still classified in severe (D2) or worse drought: Colorado, 89% (down from 100%); Wyoming, 84% (down from 86%); and Utah, 52% (down from 66%).

Current Snowpack and Streamflows

The distribution of precipitation in February tended to reduce the disparity among the region’s basin snowpacks by March 1, with the basins that had been the driest (eastern Colorado and eastern Wyoming) seeing gains and those that had been the wettest (most of Utah, and northwestern Wyoming) seeing losses compared to the average conditions. In Colorado, February brought mainly near-average accumulations, so that March 1 snowpack values, at 65–80% of average, were similar to the February 1 values, with slight declines in the southwestern basins and increases east of the Continental Divide. In Wyoming, the western portion of the state saw below-average accumulation and March 1 snowpack levels declined significantly, to 79–91% of average. Across the rest of the Wyoming, March 1 snowpack values were generally improved, if slightly, compared with February 1.  In Utah, however, all basins saw below-average accumulation, leading to March 1 snowpack values that were significantly lower than February 1, at 73–96% of average. Overall, nearly all basins in the region have below-average March 1 snowpacks.

In the maps of current streamflows across the three states, many gages are still ice-affected and not reporting, especially in Wyoming. Of the gages that are reporting, the “normal” category is most frequently reported, but there are many more gages in the below-normal categories than above-normal, particularly in Colorado. The Green River near Greendale, UT gage, was in the 20th percentile, at 75% of the median flow for March 5. The Colorado River near the CO-UT State Line was in the 19th percentile, at 70% of the median flow for March 5.

Spring-Summer Streamflow Forecasts

The March 1 spring-summer streamflow forecasts of the season were just released by NOAA CBRFC and the NRCS. The NRCS Westwide Streamflow Forecast Map shows that most basins in our region are now expected to have much-below-average (50-69%) spring and summer runoff, with basins in central and southwestern Utah and northern Wyoming being in relatively better shape with forecasted below-average (70-89%) or near-average (90-109%) runoff. Several basins have slipped to the far-below-average category (25-49%) category, including overall Lake Powell inflows; the official CBRFC March 1 forecast has been reduced to 3.4 MAF, only 49% of average, compared to the February 1 forecast of 3.85 MAF. The very dry runoff outlook for the region reflects both the below-average snowpacks and the unusually dry soil moisture last fall, which is expected to significantly reduce runoff efficiency in the spring. (NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC.)

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks for March, released on February 28 by NOAA CPC, show no tilt for precipitation for our region for March, except for the extreme southwestern corner of Utah, and a tilt towards colder-than-average conditions for March over the region, especially Wyoming. The latest seasonal Climate Outlooks released on February 21 by NOAA CPC show a tilt towards drier-than-average conditions spring and early summer across most of the region, with the area of dry tilt covering more of the region than last month’s outlooks for spring. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the winter and spring seasons for at least Utah and Colorado, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook released February 21 projects that the drought conditions across our region will persist, through at least May 2013, and as seen in the previous outlook, some improvement is expected in far northern Wyoming.

The latest PSD Precipitation Forecast Guidance ("SWcast"), released March 5 for April–June 2013 conditions, forecasts a wet tilt for spring and early summer for all of Colorado and much of Utah, with the strongest tilt towards wet conditions (>10%) over western and south-central Colorado and far eastern Utah. A modest tilt towards dry conditions is forecasted for far northern Utah. (We will try to update soon with more explanation of the SWcast and why it might differ from the CPC forecast.)

As has been the case since fall 2012, ENSO conditions are not exerting much influence on the climate system, and thus the seasonal forecasts. ENSO indicators continue to show ENSO-neutral conditions on the cool (La Niña) side of neutral. The models in IRI's mid-February ENSO Prediction Plume indicate a consensus towards ENSO-neutral conditions continuing through next summer and fall.

 

February 4, 2013 (updated February 6 and 7)


Highlights

January Precipitation and Temperatures, and Current Drought

January saw a very uneven distribution of precipitation across our region, in both space and time. The first three weeks of January were quite dry, with two systems in the last week generating most of the month’s moisture. Most mountain areas in western and central Colorado ended up with above-average precipitation, as did eastern Utah and north-central Wyoming. Drier-than-average conditions predominated in southern Wyoming and, yet again, in eastern Colorado. The HPRCC Water Year Precipitation map shows that while January aided some areas, most of the region remains drier than average since October 1. Southeastern Colorado is still the driest area in the region, with less than 50% of average October–January precipitation.

Perhaps the most notable aspect of January’s weather was the cold anomaly over most of Utah and portions of western Colorado, with monthly temperatures more than 10°F below average. Intrusions of Arctic air were followed by upper-level ridging and calm winds, leading to persistent surface inversions. Moab, Utah ended up with a record-cold January monthly average of 8.6°F, or 18°F below normal, and more than 5°F below the previous record. In northern Utah, a particularly strong inversion caused a serious air pollution episode from about the 18th to the 26th.

The latest US Drought Monitor, representing conditions as of January 29, shows very little change in drought conditions since January 1. The vast majority of the region is still classified in severe (D2) or worse drought: Colorado, 100% (up from 95%); Wyoming, 86% (unchanged), and Utah, 66% (up from 64%).

Current Snowpack and Streamflows

The dry first three weeks of January saw regional snowpacks decline with respect to the typical trajectory—especially in Colorado, where this slippage was dramatic. But the final, snowy, week salvaged the month for most basins, bringing conditions close to where they were on January 1 in terms of percent of average. The NRCS Current Basin Snowpack map on February 1 showed that Colorado and southeastern Wyoming basins remain well below to below average, with the South Platte and Arkansas near record-low levels at about 60% of average. In the rest of Wyoming and in Utah, snowpacks are generally near-average or slightly above average. In Utah’s Wasatch Range, the mountain snowpack slipped to about 85% of average even as the urban areas and foothills experienced above-average snowfall, thanks to “upside-down” storms. The February 1 basinwide snowpack for the Upper Colorado River above Lake Powell was 84% of average, compared to 86% of average on January 1.

In the maps of current streamflows in the three states, most gages are ice-affected and not reporting, as is normal for this time of year. The Green River near Greendale, UT gage, was in the 40th percentile, at 81% of the median flow for February 1.

Spring-Summer Streamflow Forecasts

See the previous briefing for details of the January 1 streamflow forecasts for spring–summer 2013. The general outlook for the region is drier than average, reflecting the snowpack anomalies. The next (February 1) streamflow forecast map should be posted by NRCS (and on the Dashboard) around February 10th; we expect no major changes in the regional outlook from the January 1 forecasts. The Colorado Basin River Forecast Center (CBRFC) has released their official February 1 forecasts here; there are slight improvements in the forecasted flows for the San Juan and Uncompahgre basins compared with January 1, but the forecasts are generally lower than on January 1 elsewhere in the Upper Colorado Basin and eastern Great Basin. The official CBRFC February 1 forecast for April–July Lake Powell inflows has slipped to 3.85 MAF, only 54% of average, compared to the January 1 forecast of 4.4 MAF. (NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC.)

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks for February, released on January 31 by NOAA CPC, shows a wet tilt for most of Utah and western Colorado through February, reflecting the weather model guidance showing a tendency towards troughs (= moisture) over that area in the first half of February. It is also consistent with the wet forecast for our region seen in the 5-day QPF for the February 6–11 period. The latest seasonal Climate Outlooks released on January 17 by NOAA CPC continue to show a slight tilt towards drier-than-average conditions for the late winter and spring in the southern portion of our region, with the area of dry tilt covering more of Colorado and Utah than the previous outlooks. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the winter and spring seasons, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook released January 17 projects that the drought conditions across our region will persist, through at least April 2013, with a slight change from previous outlooks, in that some improvement is expected in far northern Wyoming.

The latest PSD Precipitation Forecast Guidance ("SWcast"), released January 23 for January–March 2013 conditions, continues to forecasts a dry tilt in late winter for most of Utah and Colorado, with the strongest tilt towards dry conditions (>10%) in north-central Colorado—though the model skill is marginal in northern Colorado for this season. A modest tilt towards wet conditions is forecasted for far northern Utah. Overall, this dry outlook for Utah and Colorado is mostly unchanged from the forecast made in November, and is consistent with a continued cold North Pacific (PDO-) in conjunction with a warm North Atlantic (AMO+).

As has been the case since last fall, the seasonal forecasts are not being influenced by ENSO, since the ENSO indicators continue to show ENSO-neutral conditions—though tipping most recently towards La Niña conditions—and the models in IRI's mid-January ENSO Prediction Plume show a consensus towards ENSO-neutral conditions continuing through next summer.

 

January 23, 2013

(see addition January 25, at bottom)


Current Snowpack

After strong gains in December, an extended stretch of drier-than-normal weather across the region since January 1 has caused snowpacks to slip backwards with respect to average conditions, especially in Colorado and eastern Wyoming. The Current Basin Snowpack map from NRCS shows Colorado basin snowpacks ranging from 55–68% of average, and mainly from 30–70% of average in eastern Wyoming. In Utah and western Wyoming, nearly all basins have between 80–100% of average snowpack. The basinwide snowpack for the Upper Colorado River above Lake Powell as of January 23 is at 71% of average, down sharply from 86% of average on January 1.

Spring-Summer Streamflow Forecasts

The first spring-summer streamflow forecasts of the season, valid January 1, were released by NOAA CBRFC and the NRCS in early January. The NRCS Westwide Streamflow Forecast Map shows most basins in our region expected to have below-average (70-89%) or much-below-average (50-69%) spring and summer runoff, with several basins expected to have near-average (90-109%) runoff in central Utah and northwestern Wyoming. IMPORTANT NOTE: While NRCS and NOAA continue to collaborate on streamflow forecasts, the forecast values are no longer being strictly coordinated between NRCS and some of the RFCs, including the CBRFC. For example, the NOAA CBRFC January 1 forecast for Lake Powell April-July inflows is 4400 KAF, 61% of average. The NRCS forecast for the same point is for 4000 KAF, 56% of average. Also note that all of the January 1 forecasts do not reflect the declines in snowpack since the first of the month.

Seasonal Climate and Drought Forecasts

The latest monthly and seasonal Climate Outlooks released on January 17 by NOAA CPC continue to show a slight tilt towards drier-than-average conditions for the late winter and spring in the southern portion of our region, with the area of dry tilt covering more of Colorado and Utah than the previous outlooks. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the winter and spring seasons, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook released January 17 projects that the drought conditions across our region will persist, through at least April 2013, with a slight change from previous outlooks, in that some improvement is expected in far northern Wyoming.

[Added January 25:] The latest PSD Precipitation Forecast Guidance ("SWcast"), released January 23 for January–March 2013 conditions, continues to forecasts a dry tilt in late winter for most of Utah and Colorado, with the strongest tilt towards dry conditions (>10%) in north-central Colorado—though the model skill is marginal in northern Colorado for this season. A modest tilt towards wet conditions is forecasted for far northern Utah. Overall, this dry outlook for Utah and Colorado is mostly unchanged from the forecast made in November, and is consistent with a continued cold North Pacific (PDO-) in conjunction with a warm North Atlantic (AMO+).


January 3, 2013

Highlights

December Precipitation and Temperatures, and Current Drought

December was wetter overall in our region than November and October, with most mountain regions seeing above-average precipitation for the month, including western and central Colorado, western Wyoming, and far northern Utah. There were also large areas with drier-than-average conditions, especially eastern Wyoming and most of eastern Colorado. Despite the December gains in many areas, the HPRCC Water Year Precipitation map shows that after the first quarter of the 2013 water year, nearly all of the region is drier than average, with some areas like southeastern Colorado seeing less than 50% of average October–December precipitation. December was cooler than average over most of the region, with the wetter areas generally seeing the below-average temperatures, and the drier parts of Wyoming and Utah being warmer than average. The latest US Drought Monitor, representing conditions as of January 1, shows a modest reduction in the area of severe (D2) and extreme (D3) drought conditions since late November, but the vast majority of the region is still classified in severe (D2) or worse drought: Colorado, 95%; Wyoming, 86%, and Utah, 66%.

Current Snowpack and Streamflows

As reported in the December 21 briefing, snowpacks across Colorado saw large gains in December. Even so, the NRCS Current Basin Snowpack map shows that Colorado—and southeastern and north-central Wyoming—still lag well behind average conditions for early January. In the rest of Wyoming and in Utah, snowpacks kept pace with normal accumulations during December and are near-average or slightly above average. The January 1 basinwide snowpack for the Upper Colorado River above Lake Powell was 86% of average, up sharply from 60% of average on December 1.

In the maps of current streamflows in the three states, note that most gages are now ice-affected and not reporting, as is normal for this time of year. The gages that are reporting are mostly showing normal (green) streamflows, below-normal (yellow), or much-below normal (brown) flows for the date, with very few in the above-normal categories. The Colorado River near Cisco, UT gage, was in the 13th percentile, at 76% of the median flow for December 2.

Seasonal Climate and Drought Forecasts

As reported in the December 21 briefing, the latest monthly and seasonal Climate Outlooks released on December 20 by NOAA CPC are now showing a slight tilt towards drier-than-average conditions for the winter and early spring in the southern portion of our region. The IRI's mid-December ENSO Prediction Plume shows a strong model consensus that ENSO-neutral conditions will continue through next spring, and only a slight chance of an El Niño or La Niña event emerging in that time frame. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the winter and early spring season, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook released January 3 once again projects that the drought conditions across our region will persist, through at least March 2013.


December 21, 2012

Current Snowpack

More favorable storm tracks since December 1 have led to widespread increases in the snowpack across the region, with the most dramatic gains being seen in Colorado and eastern Utah. The Current Basin Snowpack map from NRCS shows Colorado basin snowpacks ranging from 58–81% of average, compared to 30–50% as of December 1. Utah basin snowpacks are all near or above average, while Wyoming basin snowpacks are near or above average except in the southeast corner of the state, where they are below average. The basinwide snowpack for the Upper Colorado River above Lake Powell as of December 21 is at 86% of average, up from 60% of average on December 1.

Seasonal Climate and Drought Forecasts

The latest monthly and seasonal Climate Outlooks released on December 20 by NOAA CPC are now showing a slight tilt towards drier-than-average conditions for the winter and early spring in the southern portion of our region. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the winter season, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook released December 20 again projects that the drought conditions across our region will persist, through at least March 2013.

December 3, 2012

Highlights

November Precipitation and Temperatures, and Current Drought

November was again much drier than average across most of the region. Most of eastern and central Colorado, southeast Wyoming, and eastern Utah saw less than 25% of average precipitation for the month. Conditions were wetter-than-average in north-central and southwest Wyoming and portions of northern Utah. According to the HPRCC Water Year Precipitation map, the first two months of the 2013 water year have left nearly all of the region drier than average, with most of Colorado and eastern Utah seeing less than 50% of average October–November precipitation. November was also a warm month, with temperatures 2° to 6°F above average over most of the region and up to 10°F above average in south-central Wyoming. The latest US Drought Monitor, representing conditions as of November 27, shows nearly all of the region still classified in severe (D2) or worse drought conditions. There was little change in the drought conditions across the region during November; a small pocket of D1 in north-central Colorado worsened to D2.

Current Snowpack and Streamflows

We are now far enough into the snow season (on average, 20-25% of seasonal accumulation occurs by December 1) that the percent-of-average data reported in the Current Basin Snowpack map from NRCS reliably reflect conditions on the ground. The regional snowpack map shows a pronounced difference between the generally near-average conditions in Wyoming and Utah, and the very low snowpacks in far eastern Utah and across Colorado. The Colorado statewide snowpack as of December 1 was around 40% of average, which is near the lowest level recorded since the mid-1980s. (Of the six years since 1986 with similarly low early-season snowpack across Colorado, two years (2008 and 2009) rebounded to above-average snowpacks by April 1, while one (2010) recovered to near-average conditions, and the remaining three remained well below average through the spring, including 2000 and 2002.) The December 1 basinwide snowpack for the Upper Colorado River above Lake Powell was about 60% of average.

Current streamflows in the three states reflect the gradient in recent precipitation and snowpack, with Wyoming gages generally reporting normal (green) streamflows for the date, with more gages in the below-normal (yellow) and much-below normal (brown) categories in Utah, and yet more in Colorado. The Colorado River near Cisco, UT gage, was in the 13th percentile, at 76% of the median flow for December 2.

Seasonal Climate and Drought Forecasts

As reported in the previous briefing, the latest monthly and seasonal Climate Outlooks released on November 15 by NOAA CPC are showing equal chances (EC) for above-normal or below-normal precipitation for the December through March period, with this lack of "tilt" reflecting the strong likelihood of ENSO-neutral conditions continuing through this period, as seen in the IRI's mid-November ENSO Prediction Plume. If this occurs, it will be the first ENSO-neutral winter since 2003-04. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the winter season, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook released November 15 projects that the drought conditions across our region will persist through at least February 2013.

The latest PSD Precipitation Forecast Guidance ("SWcast"), released November 19 for January–March 2013 conditions does find a signal in the pattern of past years with similar ocean-atmosphere conditions, apart from ENSO, and forecasts a dry tilt over that period for most of Utah and Colorado, with the strongest tilt towards dry conditions (>10%) in north-central Colorado—though the model skill is marginal in northern Colorado for this season and lead-time. A modest tilt towards wet conditions is forecasted for far northern Utah. Overall, this is a drier outlook for Utah and Colorado than the January–March forecast issued in late September, due to the now lower (almost zero) probability of El Niño while still having a warm North Atlantic Ocean and cold eastern North Pacific Ocean.

November 15, 2012

The latest monthly and seasonal Climate Outlooks released today (November 15) by NOAA CPC look very similar to those earlier this fall, showing equal chances (EC) for above-normal or below-normal precipitation for the December through March period. This lack of "tilt" for our region reflects that ENSO indicators in the tropical Pacific such as Nino 3.4 sea surface temperatures, after briefly flirting with El Niño, have returned to neutral conditions, and the vast majority of ENSO forecast models compiled for IRI's mid-November ENSO Prediction Plume call for ENSO-neutral conditions to continue through the winter. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures for the winter season, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook, also released November 15, projects that the drought conditions across our region will persist through February.

November 6, 2012

October saw the dryness of the 2012 water year continue, with nearly all of the region drier than average since October 1 except for scattered areas in southern and western Wyoming and extreme northeast Utah, according to the HPRCC Water Year Precipitation map. Portions of northwest Colorado, southern Colorado, and central and southern Utah saw less than 25% of average precipitation for the month. The latest US Drought Monitor, released November 1, shows nearly all of the region still classified in severe (D2) or worse drought conditions. There was little change in the drought conditions across the region during September.

We are still very early in the snow season, and the long-term average SWE for November 6 at many SNOTEL sites is less than 1". Thus the percent-of-average data reported in the Current Basin Snowpack map from NRCS may not be a reliable measure of conditions. That said, examining only reports from the high-elevation/high-accumulation SNOTEL sites confirms the impression from the map that the snowpack is above-average in northern Utah, and generally below average in the rest of the region, with Colorado basins being well below average except in the north-central mountains.

Compared to early October, there are now more stream gages across the three states reporting below-normal (yellow) and much-below normal (brown) current streamflows, especially in western Colorado and northern and eastern Utah. Four gages in Colorado and one in Wyoming are showing record-low flows for the date (November 5).

The latest monthly and seasonal Climate Outlooks released on October 18 by NOAA CPC continue to show equal chances (EC) for above-normal or below-normal precipitation for the October through January period, reflecting the likelihood of either ENSO-neutral or weak El Niño conditions during this period, as seen in the IRI's mid-October ENSO Prediction Plume. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures, consistent with the long-term trend towards warmer conditions. [The preceding text is unchanged from the October 23 briefing]. The latest CPC Seasonal Drought Outlook released November 1 projects that the drought conditions across our region will persist through at least January 2013.

October 23, 2012

The latest monthly and seasonal Climate Outlooks released on October 18 by NOAA CPC continue to show equal chances (EC) for above-normal or below-normal precipitation for the October through January period, reflecting the likelihood of either ENSO-neutral or weak El Niño conditions during this period, as seen in the IRI's mid-October ENSO Prediction Plume. The CPC Climate Outlooks continue to show enhanced odds for above-normal temperatures, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook also released October 18 projects that the drought conditions across our region will persist through at least December.

Thus far in October (and the beginning of the 2013 water year), according to the HPRCC Water Year Precipitation map, precipitation has been well below-average across the region except for small areas in north-central Colorado and southwestern Utah. Over the next 4-5 days a storm system is forecasted to bring significant precipitation to northern and eastern Colorado, northern Utah, and much of Wyoming.

As of October 23, the Current Basin Snowpack map from NRCS shows a misleading picture for Utah as there are are actually very few SNOTEL sites in that state, and across the region, reporting any SWE on the ground. [Correction 10/24: The deleted wording did not distinguish sites that were not reporting any data from sites that were reporting zero SWE. And more sites are now reporting data on 10/24, compared to the previous day. See this SNOTEL map from NRCS for a clearer depicton of current site-level data across the West.] Most SNOTEL sites across the region are reporting below-average precipitation since October 1, consistent with the HPRCC precipitation map, which does not include SNOTEL data.

October 1, 2012

September was drier than average across Wyoming, western Colorado, and much of Utah. Wetter-than-average conditions prevailed in central Colorado, far western Utah, and other parts of Utah. Over the just-completed 2012 water year, nearly all of the region was drier than average, with about half the region receiving less than 70% of average precipitation. The latest US Drought Monitor reflects the widespread long-term dryness, with nearly all of the region mired in severe (D2) or worse drought conditions, including small areas of D4 in far northeastern and southeastern Colorado.

The very first snowpack accumulations of the season are being reported by the SNOTEL network. The majority of stream gages reporting across the three states have flows in the normal range, but with many gages at below-normal and much-below normal flows also scattered throughout the region.

The latest monthly and seasonal Climate Outlooks from NOAA CPC show equal chances (EQ) for above-normal or below-normal precipitation for the October through January period, and enhanced odds for above-normal temperatures during that period, consistent with the long-term trend towards warmer conditions. The latest CPC Seasonal Drought Outlook projects that the drought conditions across our region will persist through at least December. The latest experimental precipitation forecast guidance from NOAA ESRL PSD shows enhanced chances for wetter-than-average conditions in eastern Colorado for the October-December period.

This summer, conditions in the tropical Pacific appeared to be in a rapid transition to El Nino, but that transition has slowed in the past month, and NOAA has not yet announced an El Nino. The most recent ensemble of ENSO prediction models forecasts that conditions will either remain on the warm side of ENSO-neutral, or transition to weak El Niño conditions through the winter season.