February 14, 2014

Highlights

• January precipitation was highly variable over the region, with wetter-than-average conditions across northern and central Wyoming and the northern two-thirds of Colorado. Potent systems in early February brought heavy precipitation to most mountain areas, especially northern Utah, northern Colorado, and southwestern Wyoming.
• As of February 13, snowpack conditions have improved significantly since late January. All basins in Wyoming, all but one basin in Colorado, and basins in northern and south-central Utah have near-normal to above-normal SWE (>90% of median); most basins in Wyoming and northern Colorado are at over 120% of median SWE.
• The February 1 spring-summer streamflow forecasts call for northern and central Colorado, and northern and eastern Wyoming to have near-average or above-average spring and summer runoff.  South-central and southwestern Colorado, southwestern Wyoming, and Utah are expected to have below-average to much-below-average spring and summer runoff. These forecasts do not reflect the most recent improvement to the snowpack.

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 . 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  . 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 , 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  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 , Utah , and Wyoming show 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 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 region for January . 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 and March–May periods . The latest CPC Seasonal Drought Outlook released January 16  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  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  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   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.”