January 23, 2013

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+).

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