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, April 1, 2010

Green Water Supply Outlook, April 1, 2010


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

Contents

Green Summary




*Median of forecasts within each basin.


Upper Green Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through March precipitation was 70 percent of average in the Upper Green basin. March precipitation was 80 percent of average.

Snow:
April 1st snow water equivalent was near 60 percent of average in the basin as a whole.
--- Upper Green basin snow water equivalent plot.

Streamflow:
March streamflow was near 85 percent of average.

Soil Moisture:
Modeled soil moisture states ranged from below average to near average heading into the winter.

Climate Forecasts:
Climate forecasts were not a factor because there is not a strong correlation between El Nino conditions and winter precipitation in the Upper Green basin.

Forecast Summary:
Due to below average seasonal precipitation to date and much below average April 1st snow water equivalent values the April through July streamflow volume forecasts are much below average at this time. These forecasts have dropped slightly and now range between 38 and 66 percent of average, with a median value of 50 percent.



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

Yampa/White Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through March precipitation was 80 percent of average in the Yampa/White basin. March precipitation was 75 percent of average.

Snow:
April 1st snow water equivalent was 75 percent of average in the basin as a whole.
--- Yampa basin snow water equivalent plot.

Streamflow:
March streamflow was near 60 percent of average.

Soil Moisture:
Modeled soil moisture states were near average heading into the winter for the Little Snake and White River basins. Modeled states ranged from below average to near average heading into winter for the Yampa basin.

Climate Forecasts:
Climate forecasts were not a factor because there is not a strong correlation between El Nino conditions and winter precipitation in the Yampa/White basin.

Forecast Summary:
Due to below average seasonal precipitation to date and below average April 1st snow water equivalent values the April through July streamflow volume forecasts are below average at this time. These forecasts have dropped slightly and now range between 54 and 76 percent of average, with a median value of 70 percent.



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

Duchesne Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through March precipitation was 70 percent of average in the Duchesne basin. March precipitation was 75 percent of average.

Snow:
April 1st snow water equivalent was 70 percent of average in the basin as a whole.
--- Duchesne basin snow water equivalent plot.

Streamflow:
March streamflow was 85 percent of average.

Soil Moisture:
Modeled soil moisture states were much below average to below average heading into the winter.

Climate Forecasts:
Climate forecasts were not a factor because there is not a strong correlation between El Nino conditions and winter precipitation in the Duchesne basin.

Forecast Summary:
Due to below average seasonal precipitation to date and below average April 1st snow water equivalent values the April through July streamflow volume forecasts are much below average at this time. These forecasts have dropped slightly and now range between 45 and 75 percent of average, with a median value of 65 percent.



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

Lower Green Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through March precipitation was 95 percent of average in the headwaters of the Lower Green basin. March precipitation was 100 percent of average.

Snow:
April 1st snow water equivalent was 70 percent of average in the basin as a whole. The Price and San Rafael headwaters did not receive as much snow as those further to the south.
--- Price basin snow water equivalent plot.

Streamflow:
March streamflow was near 80 percent of average.

Soil Moisture:
Modeled soil moisture states were much below average heading into the winter.

Climate Forecasts:
Climate forecasts were not a factor because there is not a strong correlation between El Nino conditions and winter precipitation in the Lower Green basin.

Forecast Summary:
Due to the below average April 1st snow water equivalent values, and the much below average soil moisture heading into winter the April through July streamflow volume forecasts are much below average at this time. These forecasts have dropped slightly and now range between 44 and 60 percent of average, with a median value of 50 percent.



* 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: William Reed