New 1981-2010 Averages being used this year.
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.Upper Colorado Water Supply Outlook, January 1, 2012

Upper Colorado Water Supply Outlook, January 1, 2012


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

Contents

Upper Colorado Summary




*Median of forecasts within each basin.


Upper Colorado Mainstem Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through December precipitation was near 70 percent of average in the Upper Colorado mainstem basin. The new water year started well with above average precipitation in October; however, November precipitation was below average and then December precipitation was just 35 percent of average.

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

Streamflow:
December streamflow was near 110 percent of average.

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

Climate Forecasts:
La Nina climate conditions exist but these do not show a strong correlation with winter precipitation in the Upper Colorado mainstem basin, and therefore were not influential in the development of streamflow volume forecasts.

Forecast Summary:
Because of the below average November and, especially, December precipitation, as of January 1 both the seasonal precipitation and snow water equivalent are much below average at 70% and 60%, respectively. However, due to a very good runoff season last year and a wet October, above average soil moisture conditions existed in the Upper Colorado mainstem heading into the winter season. Therefore, current April through July streamflow volume forecasts range between 72 and 86 percent of average with a median value of 80 percent.



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

Gunnison Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through December precipitation was 75 percent of average in the Gunnison Basin. Above average precipitation occured in October. Dry conditions and much below average precipitation occurred in November.

December precipitation was also much below average, ranging from 30 percent of average in the East River watershed to 70% of average in the Uncompaghre watershed. The Gunnison basin-wide average for December was 50%.

Snow:
January 1st snow water equivalent was 65 percent of average in the Gunnison basin.

Gunnison Basin snow water equivalent plot

Streamflow:
December streamflow volumes ranged from 85 to 90 percent of average.

Soil Moisture:
Modeled soil moisture states were above average entering the winter season.

Climate Forecasts:
La Nina climate conditions exist but these do not show a strong correlation with winter precipitation in the Gunnison Basin, and therefore were not influential in the development of streamflow volume forecasts.

Forecast Summary:
A wet October was followed by drier condtions in November and December. Seasonal precipitation was near 75 percent of average as of January 1st, with a basin snow water equivalent value near 65 percent of average. High runoff in 2011 and a wet October resulted in above average soil moisture in the Gunnison Basin entering the winter season, impacting the forecasts. April-July streamflow runoff volumes are expected to range between 60 and 80 percent of the 1981-2010 average as of January 1st.



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

Dolores Basin Conditions

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through December precipitation was 90 percent of average. Precipitation was above average in October and much below average in November.

December precipitation was near 90% of average.
Snow:
January 1st snow water equivalent was 85 percent of average in the Dolores Basin.

Dolores Basin snow water equivalent plot

Streamflow:
Many streamflow gages do not function well during the winter. December streamflow volumes in the Dolores River Basin have been estimated near 60% of average.

Soil Moisture:
Modeled soil moisture states were near to above average entering the winter season.

Climate Forecasts:
La Nina climate conditions exist but does not show a strong correlation with winter precipitation in the Dolores Basin. Therefore, it was not influential in the development of streamflow volume forecasts.

Forecast Summary:
Near to above average soil moisture existed in the Dolores River Basin entering the winter season. Above average precipitation occurred in October. Precipitation was much below average in November and near to below average in December. Seasonal precipitation was 90 percent of average on January 1st with snow water equivalent near 85 percent of average. April-July streamflow runoff volumes are expected to range from 70 to 80 percent of the 1981-2010 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: Brenda Alcorn, Greg Smith