Much above average rainfall in Utah and western Wyoming during August caused some improvement to drought conditions in the Intermountain West, but drought persists across nearly the entire region except eastern Colorado. Improvements to drought conditions were aided by a return to near normal temperatures during August. Despite near-normal August temperatures, much of Utah and parts of western Colorado and Wyoming experienced record hot summer (June-August) temperatures. There is a 60 - 80% probability of La Niña conditions developing during fall and persisting through winter.
Heavy monsoonal rains in Utah and Colorado during July led to above average precipitation, slight improvements to drought conditions and flooding. Most of the region experienced above average temperatures in July. Drought conditions improved slightly in Utah, but significantly worsened in parts of Wyoming. Despite above average July precipitation in much of the region, July streamflow in northern Utah rivers was at a record low and seasonal streamflow volume for many regional rivers was just above record low amounts.
During June, extremely high temperatures in Utah and Wyoming fueled the persistence of drought and drought expansion in northern Utah and northern Wyoming. A surge of monsoonal moisture caused above average precipitation in southwestern Colorado. Seasonal streamflow volume in nearly all of the region’s rivers was extremely low in 2021. Most Intermountain West rivers, except for those east of the Continental Divide in Colorado, saw near-record low streamflow volume.
During May, much above average precipitation removed drought conditions across Colorado east of the Continental Divide and in southwestern Wyoming. Regional drought conditions persist west of the Divide where D3 and D4 drought cover 90 % of Utah and much of western Colorado. Streamflow forecasts for much of the region are among the five driest on record and the forecasted April-July inflow forecast for Lake Powell is 25% of normal.
May - July streamflow volumes are forecasted to be less than 60% of average in the Upper Colorado River Basin and less than 50% of average in the Great Basin. The May - July inflow of Lake Powell is forecasted to be 28% of normal. Regional precipitation in April was below average and temperatures were slightly below average. Parts of western Colorado recorded a record dry April. Drought covers 90% of Colorado, Utah and Wyoming and seasonal forecasts predict a higher probability for below average precipitation and above average temperature for the next three months which suggests persistence and, potentially, worsening of drought. Wetter conditions with near-to-above normal snowpack and seasonal streamflow conditions and improvements to drought conditions exist in northern Wyoming.
A large upslope storm led to above average March precipitation in eastern Colorado, eastern Utah and southeastern Wyoming. Drought conditions east of the Continental Divide generally improved by one category and many river basins in these areas have near normal seasonal runoff forecasts. March was dry for much of the Upper Colorado River and Great Basins, drought conditions persisted and seasonal runoff forecasts are below to much-below normal.
Above-average February precipitation in much of the region led to substantial increases in snowpack in northern Colorado, northern Utah and Wyoming. Despite gains in regional snowpack, March 1st seasonal runoff forecasts remain below to much-below normal except for locations east of the Continental Divide in Colorado and in Wyoming where forecasts are near to slightly-below average. Regional drought persisted during February, but improved by one drought category in parts of Colorado, Utah and Wyoming.
During January, most of the region experience below average precipitation and near average temperatures. Snow-water equivalent (SWE) is below average in the region with most locations at 60-80% of average SWE. February 1st seasonal streamflow volume forecasts are much below normal for the entire region. The inflow forecast for Lake Powell is 46% of average. Over 60% of the region is experiencing extreme or exceptional drought.
During December, temperatures were near normal and precipitation was generally below normal. January 1st snow-water equivalent was below normal for much of the region, especially in Utah. As a result, early season forecasts of spring runoff volume are below normal to much-below normal for the entire region except northern Wyoming. The seasonal runoff forecast for the Lake Powell inflow is only 53% of normal. Drought conditions remained unchanged, but extreme or exceptional drought covers over 60% of the region. The 2020 calendar year was one of hot drought; Utah recorded its driest and 7th hottest year and Colorado experienced its 2nd driest and 6th hottest year.
Current climate conditions and seasonal forecasts suggest that the 2021 water year is likely to be drier than average for much of Colorado, Utah and Wyoming. At the start of the 2021 water year, much of the region is under extreme or exceptional drought (D3-D4), soil moisture is extremely low and streamflow is at all-time or near-all-time lows at many locations. Extremely dry conditions to begin the 2021 water year mean that spring runoff will almost certainly be an inefficient runoff, where a normal snowpack would yield a below normal seasonal runoff volume. La Niña conditions currently exist and are extremely likely to continue this winter. La Niña typically delivers below normal precipitation to southern Colorado and Utah and above normal precipitation to northern Wyoming.
November precipitation was below normal for much of the region, leading to below average snowpack in most areas. Utah saw the least precipitation and snowpack is generally less than 70% of average. As a result, drought conditions significantly worsened in Utah; exceptional (D4) drought expanded to cover three-quarters of the state. Stream gages on the Animas, Bear, San Miguel and San Juan Rivers recorded record low average streamflow conditions in November. La Niña conditions are expected to continue throughout the winter and may lead to below average precipitation in southern Colorado and Utah.
Drought continued to dominate regional climate in October. Precipitation was below normal to much-below normal for most of the region. Snow fell in most mountain ranges during October, but drought conditions persisted or worsened, especially in Utah and Colorado. Another large wildfire broke out in Colorado; by the end of the month the East Troublesome Fire scorched over 193,000 acres and the Cameron Peak Fire had grown to over 208,000 acres. La Niña conditions are forecasted for November – March, increasing the probability of below average winter precipitation for much of Utah and Colorado and above average winter precipitation in northern Wyoming.
The 2020 water year was characterized by drier conditions and lower runoff than the drought-busting, high snowfall year that preceded. High 2019 seasonal runoff volumes left regional reservoir storage above average; reservoir storage at the beginning of the 2020 water year was 109% of average in Colorado, 127% of average in Utah and above average in Wyoming. Despite high snowfall and above average precipitation in the 2019 water year, June – September precipitation was much below average for most of the region. This left regional soil moisture values much below normal at the beginning of the 2020 water year . In northern Utah and the Upper Green River basin in Wyoming, soils were wetter than other locations, but still below average. Soil moisture values in southern Utah and western Colorado were much below average (<25th percentile).
Continued below average precipitation during September caused further worsening of drought conditions; extreme (D3) drought covers 46% and exceptional drought covers 10% (D4) of the region. Entering the 2021 water year, the current regional drought ranks among the worst in the last 20 years (2002, 2012, 2018). La Niña conditions currently exist and there is a 70-80% probability of La Niña conditions persisting through early winter. Drought conditions are expected to persist and potentially worsen as there is an elevated probability for below normal precipitation and above normal temperatures for the next three months.
Record hot temperatures and near-record to record low precipitation during August led to a major degradation of drought conditions. D3 drought expanded to cover nearly 80% of Utah, 50% of Colorado and 20% of Wyoming. D4 drought emerged in central Utah and eastern Colorado. Two large wildfires burned in Colorado during August and are now the 1st and 5th largest wildfires in state history. La Niña conditions currently exist in the eastern Pacific Ocean and there is a 75% chance of La Niña conditions continuing through the fall and winter.
During July, drier- and warmer-than-normal conditions over most of the region led to an expansion of drought coverage and increased drought severity. New areas of D3 drought emerged in Utah and Wyoming. Over 95% of the region is experiencing drought or abnormally dry conditions. An El Niño event is unlikely to develop this winter; it is likely that La Niña or neutral conditions will occur in winter and spring 2020-21.
Despite above average rain in some portions of the region, drought conditions expanded slightly and worsened by one drought category across the region. During June, areas of above average precipitation fell in parts of eastern Utah and western Colorado and Wyoming; much of Colorado, southwest Utah and eastern Wyoming saw below average precipitation. After extremely warm regional temperatures in April and May, the western half of the region experienced near-normal temperatures while eastern Colorado and Wyoming saw temperatures 2-6 degrees above normal.
Continued dry and warm conditions in the Intermountain West during May have caused a rapid melt of snowpack and a reduction in June 1st streamflow forecasts compared to May 1st forecasts. Much below average precipitation (5-50% of normal) and above average temperatures in Utah and southern Colorado have caused snowpack at many Snotel sites to melt out 10 days to one month earlier than average. June 1st seasonal streamflow forecasts have decreased by as much as 20% since May 1st and the streamflow forecast for the inflow to Lake Powell on the Colorado River decreased by 750,000 acre-feet to 57% of average. Abnormally dry and drought conditions expanded in all three states, now covering 80% of the region.
A very dry April in Utah and southern Colorado caused an acceleration of snowmelt, a decrease in forecasted seasonal streamflow volumes and a major expansion of drought in southern and eastern Colorado. While Utah and southern Colorado precipitation was much below average, near-average precipitation and near- to below-average temperatures prevailed in northern Colorado and Wyoming. Snowpack conditions are generally below to much below average in Utah and southern Colorado, but near average in northern Colorado and Wyoming. Regional May 1 seasonal streamflow forecasts are generally below average, with a few basins forecasted to have near-average or much-below-average seasonal streamflow.
Just past the typical time of peak snowpack in the Intermountain West, nearly all locations in Colorado, Utah and Wyoming have near-average to slightly above-average snowpack conditions. Seasonal runoff forecasts for the region are typically near to below average; below-average runoff conditions in southwestern Colorado and portions of Utah are in part due to low soil moisture conditions entering the current water year. Strong storms during the first half of March in the southern portion of the region led to improvements in snow conditions and runoff forecasts for the Virgin and San Juan River basins.
Despite a relatively dry February and a dry start to March, the snowpack in most of the region remains near normal. Below-average (70-90%) spring-summer streamflow is forecasted for much of the region, while near-average streamflow is forecasted in northern Utah, above-average streamflow is forecasted for the Colorado Headwaters and Yampa River basin, and much-below-average streamflow is forecasted for the San Juan River basin. Drought conditions across the region have changed little in the last month.
An unusually active storm track has led to continuing and nearly unprecedented gains in snowpack conditions for the region since mid-February. The region's snowpack is now similar to that in mid-March 2011 or 2017, which would have been hard to imagine two months ago. The March 1 seasonal runoff forecasts call for near-average (90-110%) or above average (110-130%) spring-summer runoff for the vast majority of forecast points, but these forecasts do not fully reflect the additional heavy snowfall since March 1. Drought conditions in the Four Corners and elsewhere have seen significant improvement.
Snowpack conditions have improved substantially across the region since mid-January, with most basins gaining 10-20 percentage points relative to median SWE conditions. The February 1 seasonal runoff forecasts call for below-average (70-90%) or near-average (90-110%) spring-summer runoff for the vast majority of forecast points across the region, with the NOAA forecasts anticipating lower volumes than the NRCS forecasts.
With below-normal or near-normal snowpack conditions and very low antecedent soil moisture, NOAA's January 1 forecasts call for much-below-average (50-70%) or below-average (70-90%) spring-summer runoff across nearly all of the region's basins. Unless there is significant improvement in snowpack conditions, most of the basins in Colorado and Utah that saw very low runoff in 2018 will face another year of hydrological drought.
A stormy start to Water Year 2019 has led to above-normal snowpack conditions over most of the region and some general improvement in regional drought conditions. The most drought-stricken areas in southwestern Colorado and southeastern Utah have not seen as much benefit from the early-season storms, and the snowpack is below normal in those basins.
Water Year 2018 ended with a whimper, as extremely dry and very warm conditions prevailed over the region in September. Water-year precipitation and streamflows ended up at record- or near-record-low levels across most of Utah and Colorado, accompanied by record- or near-record-high average temperatures and evaporative demand. The cool and wet start to October dampened wildfire danger and raised hopes for the new water year, but deep deficits in soil moisture and water supply persist.
Severe (D2) to exceptional (D4) drought conditions are now impacting about two-thirds of Utah and Colorado after a summer that brought little relief, with unusual warmth and below-normal rainfall continuing over most of the two states. During the June-August period, most gages in Colorado and Utah saw near-record-low streamflows.
Utah and Colorado are seeing increasing hydrological, agricultural, and ecological impacts associated with the severe (D2) to exceptional (D4) drought conditions now covering over half of both states. Recent and current streamflows in the drought-affected basins are generally 5-30% of normal, including mainstem gages on the Duchesne, Yampa, Lower Green, Colorado, Gunnison, Dolores, San Juan, and Rio Grande.
Below-normal precipitation for May and early June in most areas has clinched an extremely poor runoff season for Utah and southern and western Colorado. Meltout and peak runoff occurred 3-6 weeks earlier than normal in most basins. The very low winter and spring precipitation has led to high wildfire risk, with multiple large fires currently burning in Colorado and Utah.
An extremely poor runoff season in Utah and the southern half of Colorado is underway, with forecasted outcomes generally worse than 2012 but better than 2002. The Upper Colorado River Basin as a whole is headed for the 5th-worst runoff season since 1964, with 40% of average inflows to Lake Powell expected. Exceptional drought (D4) has emerged in the Four Corners region and the Sangre de Cristo Mountains.
Snowpack conditions in Utah and the southern half of Colorado remain very poor after below- to near-normal March precipitation. Very low spring-summer runoff is increasingly likely in these basins. Severe to extreme drought conditions have spread and now cover more than half of both states.
Even with near-normal February snowfall in many mountain areas, Utah and most of Colorado are still facing poor snowpack conditions and the strong likelihood of very low spring-summer runoff. Extreme drought has emerged in the Four Corners region and southwestern Utah, and severe drought has expanded in southeastern Colorado.
After another month of sub-par precipitation and unusually warm temperatures, moderate to severe drought conditions have settled in across nearly all of Utah and most of Colorado. At this stage of the season, the near-record-low snowpack in many basins makes very low spring-summer runoff a likely outcome, while recovery to near-average conditions is extremely unlikely.
A winter drought is developing across Utah and Colorado, with very low precipitation and poor snowpack conditions accompanied by very warm temperatures and unusually high evaporative demand. It is unlikely that the snowpack will recover to average conditions by spring, and very low spring-summer runoff is increasingly likely, especially in southern Utah and southwestern Colorado.
The snow season has gotten off to a slow start in Utah and Colorado, especially in the southern portions of those states. Many SNOTEL sites are observing their lowest or 2nd-lowest SWE on record for early December. In Wyoming, by contrast, the snowpack is near normal or above normal in nearly all basins. The outlook through December 17th is for very dry and warm weather across the region.
Multiple early-season storms have brought snow to the high country, resulting in much-above-normal SWE for early October in many basins. However, with dry conditions forecasted for the next 7-10 days, it's not clear that much of this early bounty will persist.
After an extremely dry June for the region, July brought relief in the form of above-normal precipitation for much of Colorado, southern and eastern Utah, and south-central Wyoming. Dry conditions continued in July for most of Wyoming, northern and central Utah, and northeastern Colorado. Some locations in southeastern Colorado received over 7" of rain in July, while parts of Utah, Wyoming, and Colorado received less than 0.1."
June precipitation ranged from record driest to near average in Arizona, while in New Mexico, precipitation ranged from much-below to much-above average . This difference reflects the typical progression of monsoon activity in the Southwest and the relatively late start to monsoon activity observed in much of Arizona this year. Thus far in July, precipitation has been generally above average in Arizona and below average in New Mexico. Year-to-date precipitation for 2017 shows average to above-average precipitation in all of New Mexico and much of Arizona, with a pocket of below-average precipitation in southeast Arizona .
While the vast majority of SNOTEL sites in the region have melted out, the rest are generally recording well-above-normal SWE for June 12. At these high and wet sites, the remaining snow is now melting at typical late-season rates of 1-2" of SWE per day.
April precipitation was average to above average in New Mexico, while most of Arizona was below average, including much-below average and record-dry conditions in the southwestern corner of the state. May has been dry in southern Arizona and New Mexico, while parts of northern Arizona and northern and eastern New Mexico have picked up decent precipitation relative to the normally dry May climate. Water year precipitation has been normal to above normal across most of Arizona and New Mexico aside from a small pocket of dry conditions along the Arizona-Mexico border.
A wetter-than-normal April and early May led to a bumpy snowpack trajectory through the peak(s) and into the main melt season, and as of May 11, SWE is above normal in all areas except northwestern Colorado, southeastern Wyoming, and southern Utah. The highest, wettest Snotel sites in the region appear to have just peaked, among them Grand Targhee (WY) and Snowbird (UT), both at about 60" of SWE, well above normal.
Very warm and dry conditions the first three weeks of March caused unusually early snowmelt across the region, with significant or complete meltout at low and middle elevations in many basins, and substantial SWE losses at some high-elevation sites. A return to an active storm pattern put accumulation back on track so that as of April 7th, SWE in most basins was still well above normal.
While the snow blitz of December and January slowed in February and early March, SWE values across the region are still well above median as of March 13th, except in north-central and northeastern Wyoming. Most basins are now above their median seasonal peak SWE, and some sites in northwestern Wyoming, northeastern Utah, and central and southwestern Colorado have record-high SWE for the date.
The region's snowpack accumulation has continued along a very high trajectory, with most basins at 125-180% of median SWE as of February 9th. Many sites are now above the median peak seasonal SWE in southwestern Wyoming, northern Utah, and southern and central Colorado. Only a handful of sites, mainly in central Wyoming, are lagging behind normal conditions.
Snowpack conditions have completely turned around after a grim start. A major storm kicked off the new year, and as of January 9 nearly all basins across the region have above-median SWE, with most basins at 120-170% of median. The snowpack across Colorado, Utah, and Wyoming for the date appears to be the 3rd-highest in the past 25 years, after 1997 and 2011.
November was drier than normal for most of the region, with wetter spots in central and southern Wyoming, southern Utah, and eastern Colorado. Statewide, Wyoming was in the 32nd percentile for precipitation, Colorado was in the 39th percentile, while Utah was in the 52nd percentile.
October saw a sharp gradient in precipitation across the region: all of Colorado, nearly all of Utah, and eastern Wyoming were much drier than normal, while far northern Utah and western Wyoming were much wetter than normal. Statewide, Colorado was in the 8th percentile for precipitation, while Utah was in the 25th percentile, and Wyoming was in the 84th percentile.
September was much drier than normal for Colorado, southeastern Utah, and southeastern Wyoming. The rest of Utah and Wyoming was much wetter than normal. Statewide, Colorado was in the 30th percentile for precipitation, while Utah was in the 91st percentile, and Wyoming, the 89th percentile.
July was another hotter-than-normal and drier-than-normal month for the region, though not quite as hot or dry as June. Most the region saw less than 70% of normal precipitation, while several areas had much-above-normal precipitation. Northern Utah and southern Wyoming were the driest parts of the region.
June was a very hot and very dry month for the region, with much of the region seeing less than 50% of normal precipitation, and above-normal precipitation only in scattered areas. It was the hottest June on record for Utah, the 2nd hottest for Wyoming, and the 3rd hottest for Colorado.
May's moisture was distributed unevenly across our region, but was above-normal overall, led by southwestern Wyoming, far northeastern Utah, and far northwestern Colorado recording >200% of normal precipitation.
April saw overall wetter-than-normal conditions for our region, with greater than 150% of normal precipitation over broad swaths of Wyoming, Utah, and Colorado, and only relatively small areas seeing below-normal precipitation. On a statewide basis, April's precipitation was in the 82nd percentile for Wyoming, the 77th percentile for Utah, and the 89th percentile for Colorado.
The pattern of March precipitation in our region reflected an active northerly storm track that split the region into “haves” and “have-nots," with wetter-than-normal conditions across Wyoming and in northern Utah and northern Colorado, while the southern half of the region ended up much drier than normal, especially southern and central Utah, and southeastern and southwestern Colorado. On a statewide basis, February's precipitation was in the 90th percentile for Wyoming, the 48th percentile for Utah, and the 40th percentile for Colorado.
February's precipitation was mostly below-average for the region, with one significant storm system in the first few days of February, followed by unusually dry conditions for the remainder of the month. That one storm, however, was enough so that the month ended up wetter-than-normal in eastern Colorado, southeastern and northeastern Wyoming, and parts of southern Utah. Conversely, northern and central Utah, northwestern Wyoming, and southwestern Colorado ended up much drier than normal. On a statewide basis, February's precipitation was in the 18th percentile for Utah, and the 25th percentile for Wyoming, and the 30th percentile for Colorado.
January's precipitation was another mixed bag for the region. Wetter-than-normal conditions prevailed in most of Utah, western Colorado, and southern Wyoming. Northeastern Utah, most of eastern Colorado, and northern Wyoming were drier than normal. On a statewide basis, January's precipitation was in the 73rd percentile for Utah, the 59th percentile for Colorado, and the 36th percentile for Wyoming. So far (through the 11th), February has been very wet for most of the region, though that mainly reflects the impact of the large and intense storm from the 31st to the 3rd, with warm and dry conditions prevailing since then.
December's precipitation was a mixed bag for the region. Western and northeastern Colorado, south-central Utah, and southwestern Wyoming were much wetter than normal, while western Utah, southeastern Colorado, and north-central Wyoming were much drier than normal. So far in January, the storms have favored southern Utah, southwestern Colorado, and central Wyoming.
In November, precipitation was overall above-normal for the region. Colorado was the wettest state in the region, with large areas of above-normal precipitation in the western, northeastern, and southeastern parts of the state. Wyoming and Utah didn’t fare quite as well, but both had above-normal precipitation over the majority of the state. However, several key mountain areas, including the Wasatch and the Wind River ranges, were drier than normal. On a statewide basis, November's precipitation was in the 86th percentile for Colorado, the 64th percentile for Utah, and the 60th percentile for Wyoming. The first half of December has been generally wet as well, with the storms particularly favoring northern Colorado, southeastern Wyoming, and western Utah, and few areas seeing less than 75% of normal precipitation for the period.
Across the region, October saw mainly above-normal precipitation, but there were distinct winners and losers. Surges of subtropical moisture from the southwest led to well-above-average precipitation in southern and northwestern Utah, southern and eastern Colorado, and southeastern Wyoming. Conversely, much of Wyoming, northwestern Colorado, and the rest of northern Utah received below-average precipitation for the month. Unlike in September, however, there were few areas with less than 50% of average precipitation. On a statewide basis, October's precipitation was in the 74th percentile for Colorado, the 80th percentile for Utah, and the 38th percentile for Wyoming.
September was overall a dry month for our region, with nearly all areas seeing below-average precipitation. Much of Wyoming, northeastern Colorado, and west-central Utah received less than 25% of average precipitation for the month. The only areas with above-average precipitation were in northern Utah, far western Wyoming, and parts of southern Colorado. On a statewide basis, September's precipitation was in the 19th percentile for Colorado, the 48th percentile for Utah, and the 24th percentile for Wyoming.
August precipitation was below-average overall for the region, with most of Colorado, Wyoming, and western Utah being drier than normal, while northeastern and far southern Utah, and northeastern Wyoming, were much wetter than normal. August temperatures were near average over most of the region, with few departures greater than 2°F.
July precipitation was above normal overall for the region, with southern Utah, western Colorado, and southwestern Wyoming being the wettest areas, and west-central Utah, central Wyoming, and southeastern Colorado much drier than normal. July temperatures were cooler than normal over nearly all of the region.
“Miracle May" was a hard act to follow, precipitation-wise. June reverted to a more typical pattern for our region, with distinct “haves” and “have-nots”; region-wide, precipitation was slightly above average. Due to two landfalling Pacific tropical cyclones and the timely onset of the monsoon, the “haves” were southeastern Utah and southwestern Colorado, with over 400% of average precipitation for the month in some areas. Other areas with above-average precipitation included the rest of southern Utah, central and northeastern Colorado, and northeastern Wyoming. The northern half of Utah, northwestern and southeastern Colorado, and much of western Wyoming were drier than average.
In late April the weather pattern shifted to one bringing frequent moist systems to the region. Unusually, the pattern persisted for several weeks, and so the rain and snow kept coming. And coming. And not just in a few places. Nearly the entire region received more than 200% of average precipitation for the month. The wettest areas, with over 400% of average, were southwestern Utah and portions of west-central and northwestern Utah. The driest areas—relatively—were in northern and eastern Wyoming, where “only” 125–200% of average precipitation fell. The moisture was particularly welcome in the context of the overall dry winter conditions; Salt Lake City saw as much precipitation in May (4.19”, 215% of average) as in January, February, March, and April combined.
April precipitation was quite variable around the region. Many of the areas that have had consistently dry conditions this water year were dry again in April, including southwestern Colorado, much of southern Utah, northeastern Utah, and northeastern Wyoming. Central and southeastern Wyoming, central and northeastern Colorado, and east-central Utah saw well-above-normal precipitation. Overall, the region’s mountain areas were split between wet and dry. On a statewide basis, April precipitation came out as near average in all three states: Utah was in the 40th percentile, Colorado was in the 66th percentile, and Wyoming in the 60th percentile.
March was drier than average over nearly the entire region. Storms were infrequent and when they did occur, they moved through the region quickly, and were warmer than normal. Most mountain areas received 25–75% of average precipitation, with the Wasatch Range seeing yet another very dry month with 25–50% of average. The few wet spots in the region included south-central Wyoming, and southwestern Utah.
After a big storm in the first week, the next ten days of February reverted to the overall dry weather of January. Then the upper-level pattern shifted again, and several more storms came through the region, but with very uneven results. Most of eastern Colorado ended up with much-above-average (>200% of normal) precipitation for the month, with record February precipitation and snowfall in several locations on the Front Range. South-central Colorado, southeastern Utah, and central Wyoming were also on the wet side. Northwestern Colorado, northern and central Utah, and western Wyoming saw below-average or well-below-average precipitation, with parts of the Wasatch Range experiencing the least snowy February on record.
In January, most of the region experienced drier-than-average conditions, including nearly all mountain areas. The driest areas were in western and southern Wyoming, and northwestern and north-central Colorado. Eastern Utah had the only large area with a wet anomaly for January. For the month, Wyoming ended up very dry overall, in the 8th percentile for statewide precipitation, Colorado in the 15th percentile, and Utah closest to normal, in the 33rd percentile.
In December, drier-than-average conditions in southwestern Colorado, northwestern and eastern Utah, and southern Wyoming were balanced out by areas with above-average precipitation, especially in central Wyoming and central and far eastern Colorado. For the month, Wyoming ended up in the 77th percentile for statewide precipitation, Colorado in the 73rd percentile, and Utah in the 57th percentile.
For precipitation, November brought a wide range of outcomes for the region. Nearly all of Utah experienced much-drier-than-average conditions, especially in the southern and western parts of the state. Central Wyoming was dry, while northwestern Wyoming was much wetter than average, as were portions of southern Wyoming. Many of Colorado’s mountain areas ended up above average, but eastern Colorado was very dry.
Water year 2015 began with a whimper: October was very dry over most of the region, with nearly all of Utah, most of Wyoming, and far western and northeastern Colorado receiving less than 50% of average precipitation. Only Colorado had substantial areas with above-average precipitation, mainly in the southeastern quarter. Southern and northwestern Utah saw virtually no precipitation for the month. The first half of November has been a mixed bag for the region. Many areas have seen above-average precipitation for this recent period, especially in the mountains of Colorado and Wyoming. Most of Utah has experienced much-drier-than-average conditions.
Water year 2014 concluded with a wet September for most of the region, with nearly all of Utah and most of Wyoming and Colorado seeing above-average precipitation for the month. Through October 19, water year 2015 has gotten off to a dry start across the region, with the exception of southeastern Colorado.
After a very mixed precipitation picture in July, the summer of 2014 finished on an overall wet note in August. July was drier than average across Wyoming except for the southeastern and far southwestern parts of the state. An active start to the summer monsoon season saw wet anomalies for July in most of eastern Colorado and portions of Utah, but some areas in both states saw below-average precipitation. In August, the monsoonal activity favored western Colorado and southern Utah, while a very potent Pacific storm tracked across the northern part of the region towards the end of the month. Only south-central Colorado ended the month with below-average precipitation, while much of the region saw over 200% of the average precipitation for August.
June was much drier than average across most of the region. 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.
May was wetter than average across Colorado (except the southeastern quarter), southern Utah, and far southeastern Wyoming. 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.
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. 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.
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. 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.
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. 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.
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. Even drier conditions occurred just to the south, as New Mexico and Arizona received virtually no precipitation for the month.
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.
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 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.
In October, storm tracks favored the Northern Plains and left nearly all of Wyoming with above-normal 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.
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. 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.)
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 average. 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 still shows only isolated parts of the region with above-average precipitation since October 1.
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.
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 map still shows only isolated areas with above-average precipitation since October 1.
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.
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 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.
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.
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.
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.
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.
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.
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%.
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.
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.
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.
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.
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.
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.
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