Seasonal water supply forecasts are released in several monthly (January - May) publications, including the Water Supply Outlook Report of the Colorado Basin River Forecast Center (RFC), National Weather Service. The Outlook Report is issued in three parts for each of the three major river basins in the RFC area of responsibility, the Upper Colorado, Lower Colorado, and the Eastern Great Basin.
Forecasts represent a coordinated effort between the National Weather Service, Soil Conservation Service, U.S. Bureau of Reclamation, U.S. Geological Survey, Salt River Project, and local water district managers.
Forecast period: April 1 through July 31 (most basins). Due to the earlier melt in the Lower Colorado Basin, the forecast period begins sooner and decrements each month to include only the future. Specifically, the period shifts from January 1 through May 31 at the beginning of January to April 1 through May 31 at the beginning of April.
Forecast units: thousands of acre-feet (kaf). One acre-foot is equivalent to the volume represented by one acre of area covered one foot deep (43,560 cubic feet or approximately 326,000 gallons).
30 year averages: arithmetic average of values over the 1981-2010 period.
30 year medians: median of values over the 1981-2010 period. The median, or middle value, is used in lieu of the average in the Lower Colorado Basin. With respect to the median, one half of the values are above that level and one half of them are below it.
Note: Data used in this report are provisional and subject to revision.
For more information, or to be included on the mailing list, please contact:
Colorado Basin River Forecast Center, National Weather Service 2242 W. North Temple ; Salt Lake City, UT 84116; (801)-524-5130