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.Virgin Water Supply Outlook, March 1, 2011

Virgin Water Supply Outlook, March 1, 2011


Prepared by G. Smith
NOAA, National Weather Service
Colorado Basin River Forecast Center
Salt Lake City, Utah
www.cbrfc.noaa.gov

Contents

Virgin Summary






*Median of forecasts within each basin.


Virgin Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October-February precipitation was near 225 percent of average in the Virgin Basin headwaters and ranged rom 130 to 290 percent of average elsewhere.

February precipitation was near 130 percent of average in the Virgin Basin headwaters, and 90 to 240 percent of average throughout the remainder of the Basin.

Snow:
March 1st snowpack in the Virgin River Basin ranged from 150 to 210 percent of average at elevations above 7500 feet.

Virgin River Basin Snow Plot.

Streamflow:
February streamflow volumes in the Virgin headwaters were near 110 percent the 1971-2000 median.

Soil Moisture:
Above average soil moisture conditions exist throughout the Virgin River Basin.

Climate Forecasts:
La Nina climate conditions suggest slightly decreased chances of precipitation in this area. The La Nina influence was considered in generation of these forecasts.

Forecast Summary:
Storms during the second half of February deposited additional snowfall to elevations above 6500 feet and brought Feburary precipitation totals to above average levels. The snowpack has exceeded the seasonal peak snowpack levels that typically occur in late March or early April. At some locations snowpack conditions are 200% of the average seasonal peak. Significant precipitation in October and December resulted in above average soil moisture conditions throughout the Virgin River Basin.

Despite La Nina climate conditions, that suggest increased chances for below average precipitation, conditions are more conducive for more significant runoff. April-July runoff volumes are forecast to range from near 270 to 285 percent of median, or 155 to 175 percent 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).

Precipitation Maps








Hydrologist: G. Smith