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<br />AoDmONAL INFORMATION <br /> <br />Water supply forecasts take into consideration present hydrometeorological conditions and use average <br />basin temperatures and precipitation for the forecast period. As the forecast season progresses, a greater <br />portion of the future hydrologic and climatic uncertainty becomes known and monthly forecasts become <br />more accurate. <br /> <br />Volume forecasts represent adjusted flows; that is, observed flows with upstream water use taken into <br />account. Adjusted flows will closely approximate natural or unimpaired flows. However, not all <br />upstream diversions or impoundments are measured or quantifiable. For specific adjustments used with <br />each forecast point, consult the Guide to Water Supply Forecasting. <br /> <br />The Water Supply Outlook is issued monthly January through May by the Colorado Basin River <br />Forecast Center, National Weather Service. It represents a coordinated effort between the National <br />Weather Service, Soil Conservation Service, Bureau of Reclamation, U.S. Geological Survey and local <br />water district managers. <br /> <br />DEFINITIONS: <br /> <br />Acre-Foot: <br />The volume equal to one acre covered one foot deep (43,560 cubic feet). <br /> <br />Average: <br />The arithmetic mean. The sum of the values divided by the number of values. <br /> <br />Categories: <br />Much above Average Above Average Near Average <br />130% or more III -130% 90-110% <br /> <br />Below Average <br />70-89% <br /> <br />Much below Average <br />Less than 70% <br /> <br />Forecast Period: <br />The period from April I through July 31. <br /> <br />Median: <br />The middle value. One half of the observed values are higher and half of the values are lower than this. <br /> <br />Most Probable Forecast: <br />Given the current hydrometeorological conditions to date, this is the best estimate of what the runoff <br />volume will be this season. <br /> <br />Reasonable Maximum Forecast: <br />Given the current hydrometeorological conditions, the seasonal runoff that has a ten percent (10%) <br />chance of being exceeded. <br /> <br />Reasonable Minimum Forecast: <br />Given the current hydrometeorological conditions, the seasonal runoff that has a ninety percent (90%) <br />chance of being exceeded. <br /> <br />Water Year: <br />The period from October I through September 30. <br /> <br />NOTE: Data used in this report are Drovisional and are subiect to revision. <br /> <br />For more information, or to be included on the mailing list, please contact: <br /> <br />Colorado Basin River Forecast Center, National Weather Service <br />2242 W. North Temple. Salt Lake City, UT 84116. (801) 524-5130 <br /> <br />Colorado Basin River Forecast Center - National Weather Service <br /> <br />Page 16 <br />