The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through December precipitation was 95 percent of average in the Upper Green basin. December precipitation was 50 percent of average.

Snow:
January 1st snow water equivalent was 75 percent of average in the basin.
--- Upper Green basin snow water equivalent plot.

Streamflow:
December streamflow was near 110 percent of average.

Soil Moisture:
Modeled soil moisture states indicated near average to above average soil moisture conditions last fall prior to snow accumulation.

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

Forecast Summary:
Seasonal precipitation in the Upper Green is near average as a result of much above average precipitation in October and November. However, snow water equivalent is below average due to much below average monthly precipitation in December. It is also important to note that fall soil moisture conditions were near to above average. As a result, current April through July streamflow volume forecasts range between 65 and 87 percent of average with a median value of 80 percent.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through December precipitation was 70 percent of average in the Yampa/White basin. December precipitation was 30 percent of average.

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

Streamflow:
December streamflow was near 120 percent of average.

Soil Moisture:
Modeled soil moisture states indicated above average to much above average soil moisture conditions last fall prior to snow accumulation.

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

Forecast Summary:
Seasonal precipitation is below average and snow water equivalent is much below average in the Yampa/White basins as a result of an extremely dry December. It is also important to note that fall soil moisture conditions were above to much above average. As a result, current April through July streamflow volume forecasts range between 68 and 83 percent of average with a median value of 75 percent.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through December precipitation was 90 percent of average in the Duchesne basin. December precipitation was 40 percent of average.

Snow:
January 1st snow water equivalent was 65 percent of average in the basin as a whole.
--- Duchesne basin snow water equivalent plot.

Streamflow:
December streamflow was 120 percent of average.

Soil Moisture:
Modeled soil moisture states indicated much above average soil moisture conditions last fall prior to snow accumulation.

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

Forecast Summary:
Seasonal precipitation in the Duchesne is near average as a result of much above average precipitation in October and near average precipitation in November. Snow water equivalent is much below average for the majority of the basin due to much below average monthly precipitation in December. However, the snow water equivalent for the eastern portion of the basin is near average resulting in somewhat higher forecasts. It is also important to note that fall soil moisture conditions were much above average. As a result, current April through July streamflow volume forecasts range between 63 and 104 percent of average with a median value of 80 percent.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through December precipitation was 80 percent of average in the Lower Green basin. December precipitation was 40 percent of average.

Snow:
January 1st snow water equivalent was 40 percent of average in the basin as a whole.
--- Lower Green basin snow water equivalent plot.

Streamflow:
December streamflow was near 130 percent of average.

Soil Moisture:
Modeled soil moisture states indicated near average to above average soil moisture conditions last fall prior to snow accumulation.

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

Forecast Summary:
Seasonal precipitation is below average and snow water equivalent is much below average in the Lower Green due to below average monthly precipitation in November and December. It is also important to note the fall soil moisture conditions were near to above average. As a result, current April through July streamflow volume forecasts range between 60 and 75 percent of average with a median value of 65 percent.

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).

10% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 10% chance of being exceeded. Previously referred to as "Reasonable Maximum Forecast".

50% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 50% chance of being exceeded. Previously referred to as "Most Probable Forecast".

90% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 90% chance of being exceeded. Previously referred to as "Reasonable Minimum Forecast".

Acre-Foot (af): The volume equal to one acre covered one foot deep (43,560 cubic feet). See kaf below.

Average: The arithmetic mean. The sum of the values divided by the number of values. Values from 1981-2010 are used for this publication.

Categories: Much Above Average=Greater than 130%, Above Average=111-130%, Near Average=90-110%, Below Average=70-89%, Much Below Average=Less than 70%.

CBRFC: Colorado Basin River Forecast Center.

Forecast Period: The period from April 1 through July 31, unless otherwise noted.

kaf: Thousand Acre-Feet. See Acre-Foot above.

Inflow: The volume of water that flows into a reservoir or lake.

Median: The middle value of an ordered set of values. Half of the values are higher and half of the values are lower. When the set contains an even number of values the median is the average of the two middle numbers.

NOAA: National Oceanic and Atomospheric Administration.

NWS: National Weather Service.

Water supply forecasts take into consideration present hydrometeorological conditions and use average basin temperatures and precipitation for the forecast period. As the forecast season progresses, a greater portion of the future hydrologic and climatic uncertainty becomes known and monthly forecasts become more accurate. For more information on the tools we use, consult Water Supply Forecasting Tools.

Volume forecasts represent adjusted flows; that is, observed flows with upstream water use taken into account. Adjusted flows will closely approximate natural or unimpaired flows. However, not all upstream diversions or impoundments are measured or quantifiable. For specific adjustments used with each forecast point, consult the Guide to Water Supply Forecasting.

The Water Supply Outlook is issued monthly January through May by the Colorado Basin River Forecast Center. It represents a coordinated effort between the National Weather Service, Natural Resources Conservation Service, Bureau of Reclamation, U.S. Geological Survey and local water district managers.

Note: Data used in this report are provisional and are subject to revision.

For more information, or to be included on the mailing list, please contact:

Colorado Basin River Forecast Center
2242 W North Temple
Salt Lake City, UT 84116
(801) 524-5130
www.cbrfc.noaa.gov