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Green Water Supply Outlook, January 1, 2008

Prepared by Ed Clark
NOAA, National Weather Service
Colorado Basin River Forecast Center
Salt Lake City, Utah


Green Summary

Water Supply forecasts vary over the Green River basin from below normal values in the Upper Basin (points above Flaming Gorge) to near normal conditions in the other regions. This follows water year 2007 where observed flows through out the basin were below to much below average. However, it is still early in the snow accumulation season and there is ample time for conditions to change.

*Median of forecasts within each basin.

Upper Green Basin Conditions

The Upper Green Basin stands out as having the lowest April through July Forecasts in the Colorado River Basin at this time. Despite December's above average precipitation, snow pack remains below average. After 5 years of below average flows, soils are very dry and influenced a lower forecast. This soil moisture deficit will persist through the forecast season. While climate forecasts indicate the chance for above average precipitation over the northern portion of the basin, this has yet to materialize.

* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Yampa/White Basin Conditions

Portions of the Yampa Basin are the only regions of the Green where forecasts are above 100% of average. This includes the Little Snake and Elk Rivers.

* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Duchesne Basin Conditions

Snow pack in the Uinta Basin varies greatly. While some lower elevation stations are reporting near average snow water equivalent conditions, upper elevation sites remain below average. December's monthly precipitation was above average partly due to very high amounts at low elevations station that do not normally recieve significant precipitation. Meteorological models indicate the western portion of the basin will receive significant precipitation the second weekend of January that will improve the snow pack in the short term.

* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Lower Green Basin Conditions

As in the Duchesne Basin, large amounts of precipitation at lower elevation gages pushed the monthly totals near 200 percent of average. Runoff in the Lower Green Basin, points in the Price and San Rafael drainages, is expected to be near average. Some snow sites in the along the Wasatch Plateau are above average as a result of favorable storm direction during events in early December. Slightly to the east, stations report near average conditions. As in the Western Uinta Basin, there exists the potential for significant accumulation with the storms arriving in early January.

* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

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).

Reservoir Monthly Inflow Forecasts

Monthly Streamflows

Precipitation Maps

Hydrologist: Ed Clark