The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through January precipitation was 100 percent of average in the Upper Green basin. January precipitation was 125 percent of average.

Snow:
February 1st snow water equivalent was 100 percent of average in the basin.
--- Upper Green basin snow water equivalent plot.

Streamflow:
January 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 remains near average as a result of above average and much above average precipitation in October, November, and January. Snow water equivalent has increased from below average on January 1 to near average due to the above average precipitation in January. 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 increased by 15 to 20 percent and range between 74 and 100 percent of average with a median value of 94 percent.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through January precipitation was 70 percent of average in the Yampa/White basin. January precipitation was near 60 percent of average.

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

Streamflow:
January streamflow ranged between 110 and 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:
January precipitation was much below average in the Yampa/White basins. As a result of much below average conditions for both December and January, both seasonal precipitation and snow water equivalent are much below average. It is also important to note that fall soil moisture conditions were above to much above average. As a result of another below average month, current April through July streamflow volume forecasts have decreased by 5 to 10 percent and now range between 62 and 79 percent of average with a median value of 70 percent. Forecasts are slightly higher than current snow conditions might suggest due to wet antecedent conditions.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through January precipitation was 85 percent of average in the Duchesne basin. January precipitation was 70 percent of average.

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

Streamflow:
December streamflow was 115 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 below average as a result of much below average and below average conditions in December and January. Snow water equivalent is also much below average for the majority of the basin. However, it is important to note that fall precipitation and soil moisture conditions were much above average. Wet antecedent conditions are resulting in somewhat higher forecasts for the Whiterocks and Uinta river basins. As a result, current April through July streamflow volume forecasts have decreased by 5 to 10 percent and range between 54 and 93 percent of average with a median value of 69 percent. Forecasts are slightly higher than current snow conditions might suggest due to wet antecedent conditions.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through January precipitation was 80 percent of average in the Lower Green basin. January precipitation was 85 percent of average.

Snow:
February 1st snow water equivalent was 55 percent of average in the basin.
--- Lower Green basin snow water equivalent plot.

Streamflow:
January streamflow ranged from 120 to 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, December, and January. 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 remain similar to January 1 and range between 56 and 75 percent of average with a median value of 65 percent.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through January precipitation was near 75 percent of average in the Upper Colorado mainstem basin. Above average precipitation occured in October but was followed by two months of much below average precipitation in November and December. January precipitation was near normal at 95 percent of average.

Snow:
February 1st snow water equivalent was near 70 percent of average in the basin as a whole. While it is still below average, it is an improvement from the 60 percent of average observed on January 1st.
--- Upper Colorado basin snow water equivalent plot

Streamflow:
January 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 February 1 both the seasonal precipitation and snow water equivalent are below average at 75% and 70%, 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. As a result of near normal January precipitation most forecasts are unchanged from last month. Current April through July streamflow volume forecasts range between 70 and 86 percent of average with a median value of 80 percent.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through January precipitation was 85 percent of average in the Gunnison Basin. Above average precipitation occured in October. Dry conditions and much below average precipitation occurred in November and December.

January precipitation was near to above average in upper Gunnison and East River Basins, with near to slightly below average precipitation elsewhere.

Snow:
February 1st snow water equivalent was 75 percent of average in the Gunnison basin.

Gunnison Basin snow water equivalent plot

Streamflow:
January streamflow volumes ranged from 70 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. January precipitation was near or above average at most locations. Seasonal precipitation was near 85 percent of average as of February 1st, with a basin snow water equivalent value near 75 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. April-July streamflow runoff volumes changed little from those issued January 1st and are expected to range between 60 and 80 percent of the 1981-2010 average.

The following conditions influenced this month's forecasts:

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

January precipitation ranged from 80 to 95 percent of average.

Snow:
February 1st snow water equivalent was 75 percent of average in the Dolores Basin.

Dolores Basin snow water equivalent plot

Streamflow:
January streamflow volumes in the Dolores River Basin were near 65 percent of average.

Soil Moisture:
Modeled soil moisture states were near 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 average soil moisture existed in the Dolores River Basin entering the winter season. Seasonal precipitation was near 90 percent of average on February 1st, with October the only month with above average precipitation. February 1st snow water equivalent was 75 percent of average in the Dolores Basin. April-July streamflow runoff volumes are expected to range from 65 to 80 percent of the 1981-2010 average.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through January precipitation was near average. October was wet, while November through December experienced drier than average conditions.

January was dry with a basin average precipitation near 65 percent.

Snow:
February 1st snow water equivalent for the entire basin was near 75% of average.
Animas River Basin Snow Plot.

San Juan Basin (above Navajo Reservoir) Snow Plot.

Streamflow:
Streamflow volumes for January ranged from 60% of average at the Basin outlet to near 90% of average at higher elevations.

Soil Moisture:
Modeled soil moisture has been updated since January 1st and was near to above average at highest elevations entering the winter season. Below average soil moisture conditions existed over the southern half of the basin and in tributaries further downstream.

Climate Forecasts:
La Nina climate conditions exist and a weak to moderate La Nina episode is anticipated to continue through the winter season. The La Nina climate condition suggests drier than average conditions possible over the San Juan Basin. The La Nina climate condtion was considered when developing the forecasts.

Forecast Summary:
Seasonal precipitation is near average due to a wet October. Snowpack conditions are below average due to drier weather November through January. Soil Moisture varied entering the winter season, with near or slightly above average conditions in high elevations in the northern headwaters, and below average conditions elsewhere. La Nina climate conditions suggest below average precipitation is possible over the San Juan Basin through spring. April-July runoff volumes are expected to range from 75 to 90 percent of the 1981-2010 average.

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