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San Juan Water Supply Outlook, March 1, 2010

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


San Juan Summary

*Median of forecasts within each basin.

San Juan Basin Conditions

The following conditions influenced this month's forecasts:

Seasonal October through February precipitation amounts remained near average at 110%.
February precipitation was near average with 105%.

Current snow water equivalent for the entire basin is 105%, which is near average. The Animas basin snow water equivalent was similar with 100% percent of average, while the above Navajo snow water equivalent dropped slightly from last month and was near average with 110%.
--- Animas River Basin Snow Plot.
--- Above Navajo Basin Snow Plot.

Streamflow for the entire San Juan Basin was below average in February. Seasonal streamflow since October was 50% due to the much below average summer through fall precipitation.

Soil Moisture:
Modeled soil moisture as of November 1st, 2009 was below to much below average.

Climate Forecasts:
The correlation of El Nino and April through July water volumes in the San Juan basin is so small that it did not influence the March forecast process.

Forecast Summary:
Current snowpack conditions decreased slightly in February, but remained near average. This helped drive the San Juan Water Supply April-July forecast down 5% from the previous month to 100% of average.

* 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: Tracy Cox