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<br />AoDmONAL INFORMATION <br /> <br />Water supply forecasts take into consideration present hydrometeorological conditions and use ayerage <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 upstream <br />diversions or impoundments are mcasured or quantifiable. For specific adjustments used with each <br />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 Forecast <br />Center, National Weather Service. It represents a coordinated effort between the National Weather <br />Service, Soil Conservation Service, Bureau of Reclamation, U.S. Geological Survey and local water <br />district managers. <br /> <br />DEFINITIONS: <br /> <br />Acre-Foot: <br />The yolume equal to one acre covered one foot deep (43,560 cubic feet). <br /> <br />Average: <br />The arithmetic mean. The sum of the values diyided by the number of yalues. <br /> <br />Categories: <br />Much aboye Ayerage Above Ayerage Near Ayerage <br />130% or more III -130% 90-110% <br /> <br />Forecast Period: <br />The period from April! through July 31. <br /> <br />Median: <br />The middle yalue. One half of the observed yalues are higher and half of the values are lower than this, <br /> <br />Most Probable Forecast: <br />Giyen the current hydrometeorological conditions to date, this is the best estimate of what the runoff <br />yolume will be this season. <br /> <br />Reasonable Maximum Forecast: <br />Giyen the current hydrometeorological conditions, the seasonal runoff that has a ten percent (10%) chance <br />of being exceeded. . <br /> <br />Reasonable Minirnwn 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 />Below Average <br />70-89% <br /> <br />Much below Ayerage <br />70% or less <br /> <br />NOTE: Data used in this report are provisional and are subject to reyision.' <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 />337 N 2370 W. Salt Lake City, UT 84116. (801) 524-5130 <br /> <br />Colorado Basin River Forecast Center - National Weather Service <br /> <br />Page 16 <br />