Note: This publication is currently undergoing major revisions. The current publication will be replaced with a new publication based on stakeholder requirements and scientific advances. We expect to begin sharing details on this soon. If you have input on content, format, or publication frequency at any time, please contact us at cbrfc.webmasters@noaa.gov.Green Water Supply Outlook, June 1, 2009
At the time of this publication, seasonal precipitation is near normal for most of the region. May precipitation was below average
in the Upper Green and Duchense river basins, and was near average in the Yampa/White and Lower Green river basins. Snowpack is past the seasonal peaks. Median June water
supply forecasts stayed the same in the Yampa/White and Duchense river basins, and dropped slighty in the Upper and Lower Green river basins.
*Median of forecasts within each basin.
Upper Green Basin Conditions
-Model Soil Moisture/Observed Streamflow...The November soil
moisture conditions were much below average in the Upper Green River basin. This was most likely due to prolonged dry conditions within the basin over the last nine years. Observed streamflow for the month of May was 70 percent of average.
-Snowpack/Precipitation...On June 1st, the basinwide snowpack
was 50 percent of average. However, the upper part of the basin, above 10,000 feet in elevation, is not gaged. Therefore, the actual basinwide snowpack may be greater than
reported. In the Upper Green River basin, May precipitation was 75 percent of average. However, because previous months have received above average
precipitation, the seasonal precipitation is average at this time.
-Short Term Precipitation Forecast...As of June 8th, meteorological models were predicting increased chances for below normal temperatures and above normal precipitation through
the middle of June.
-General Discussion...Most of the April through July volume forecasts stayed the same or decreased slightly from the May 1st issuance and indicate below average to near average runoff volumes for points above Flaming Gorge.
The June-July volume forecasts for Fontenelle Reservoir and Flaming Gorge Reservoir inflows are essentially the same percentage-wise as the April-July volume forecasts.
-Model Soil Moisture/Observed Streamflow...Fall soil moisture
estimates were near average in the headwaters of the Yampa and White River basin. Soil moisture deficits are not adversely effecting model guidance as much as in other regions.
While the overall monthly average maximum temperatures during May in the Yampa and White River basin were near normal, the monthly average minimum temperatures were significally above average. In addition scattered thunderstorms during the last ten days of the month helped to keep
flows up when the temperatures dropped. Therefore, observed streamflow for the month of May was 130 precent of average.
-Snowpack/Precipitation...On June 1st, the basinwide snowpack
was 35 percent of average. May precipitation was 95 precent of average. The seasonal precipitation is average at this time.
-Short Term Precipitation Forecast...As of June 8th, meteorological models were predicting increased chances for below normal temperatures and above normal precipitation through
the middle of June.
-General Discussion...The April through July volume forecasts decreased from the May 1st issuance and now the guidance indicate runoff volumes from average to above average for the Yampa and White River basin.
Given the significant runoff in May and low June 1st snowpack, the June-July volume forecasts percentage-wise are much lower ranging from 56 percent of average for the White River near Watson to 92 percentage of average for the Little Snake
River near Dixon.
-Model Soil Moisture/Observed Streamflow...Fall soil conditions in the Duchesne were similar to the Upper Green with many basins indicating much below
average conditions. While the overall monthly average maximum temperatures during May in the Duchesne River basin were near normal, the monthly average minimum temperatures were significally above average.
Therefore, observed streamflow for the month of May was 130 percent of average.
-Snowpack/Precipitation...The snowpack
in the Duchesne River basin on June 1st was essentially depleted. May precipitation was 85 percent of average. However, because previous months have received above average
precipitation, the seasonal precipitation is average at this time.
-Short Term Precipitation Forecast...As of June 8th, meteorological models were predicting increased chances for below normal temperatures and above normal precipitation through
the middle of June.
-General Discussion...Most of the April through July volume forecasts stayed the same as the May 1st issuance; however, a few increased and a few decreased reflecting the
diverse conditions within the basin. These forecasts range from average in the headwaters of the basin to much below average at downstream locations. Percentage-wise, the
June-July volume forecasts are much lower given that the snowpack is depleted.
-Model Soil Moisture/Observed Streamflow...The November soil
moisture conditions were much below average in the Lower Green River basin and continues to drive lower model guidance. Observed streamflows for the months of February, March,
and April were below average. While the overall monthly average maximum temperatures during May in the Lower Green River basin were near normal, the monthly average minimum temperatures were significally above average.
Therefore, observed streamflow for the month of May was 120 percent of average.
-Snowpack/Precipitation...The Lower Green River basin
snowpack was 15 percent of average on June 1st. May precipitation was 110 percent of average. However, because previous months have received below average
precipitation, the seasonal precipitation is average at this time.
-Short Term Precipitation Forecast...As of June 8th, meteorological models were predicting increased chances for below normal temperatures and above normal precipitation through
the middle of June.
-General Discussion...Most of the April through July volume forecasts stayed the same as the May 1st issuance with the forecasts ranging from below average to near average with the exception of Ferron Creek forecasted at much below average.
Percentage-wise, the June-July volume forecasts are much lower given that the snowpack is almost depleted.
Differences between the full period forecasts and the residual forecasts may not exactly equal the actual observed volumes due to rounding conventions (see Definitions section).