|
<br />Water Supply
<br />Outlook
<br />
<br />Published Jalntly by the Natlan'
<br />al Weather Service NOAA and
<br />the Sail Canservatlan Service
<br />USDA fallawlng the principal
<br />snaw survey dates fram Janu'
<br />ary I thraugh May 1.
<br />
<br />Caples af this publlcatian may be abtalned an request fram
<br />Natlanal Weather Service, Natlanal Oceanic and Atmaspheric
<br />Admlnlstratlan, Sliver Spring, Maryland 20910, Attentlan:
<br />Office af Hydralagy.. and the Sail Canservatlan Service, West
<br />Technical Service Center, Raam 510, 511 NW, Braadway,
<br />Partland, Oregan 97209,
<br />
<br />Same BaSIC Data and Stream,
<br />flaw Farecasts prepared by
<br />caaperating agencies are pre,
<br />sented in this bulletin, These
<br />agencies Include the Bureau af
<br />Reclamatian, Carps af Engi,
<br />neers, Farest SerVice, Natlanal
<br />Park Service, Gealaglcal Sur,
<br />vey, British Calumbla Ministry
<br />af the EnVlranment. and the'
<br />Callfarnla Department af Water
<br />Resau rces
<br />
<br />Water Supply Outlaak reparts prepared by ather agencies
<br />Include a repart far Callfarnla by the Snaw Surveys Branch,
<br />Califarnla Department at Water Resaurces, P,O, Bax 388,
<br />Sacramenta, Callfarnia 95802 - far British Calumbla by the
<br />Ministry af the Envlranment, Water Investigatians Branch,
<br />Parliament BUildings, Victaria, British Calumbia V8V IX5 - far
<br />Yukan Territary by the Department af Indian and Narthern
<br />Atfairs, Narthern Operatlans Branch, 200 Range Raad, White,
<br />harse, Yukan Territory YIA 3VI - and far Alberta, Saskatche,
<br />wan, and NW,T, by the Water Surveyaf Canada, Inland Waters
<br />Branch, 110,12 Avenue SW , Calgary, Alberta BC 1A6,
<br />
<br />To Recipients
<br />of Water Supply
<br />Outlook Reports
<br />
<br />Mast af the usable water In western states arlglnates as mauntaln snawfall. This snawfall accumulates
<br />dUring the winter and spring, several manths befare the snaw melts and appears as streamflaw, Since
<br />the runaff from preclpitatlan as snaw IS delayed, estimates af snawmelt runaff can be made well in
<br />advance af its accurrence, Fall precipltatian influences the sail maisture canditlans priar to. farmatian
<br />af snawpack and explains, In part, the effectiveness af the snawpack in producing runaff, The forecasts
<br />af natural runaff in thiS autlaak are based principally an measurements af precipitatian, snaw water
<br />equivalent. and antecedent runaff, Farecasts became more accurate as mare af the data affecting
<br />runaff are measured, All farecasts assume that climatic factars during the remainder af the snaw
<br />accumulatian and melt seasan will interact with a resultant average effect o.n rU,naff, Early seaso.n fare,
<br />casts are threfare subject to. a greater change than thase made an later dates, The repart far Western
<br />United States presents a braad picture af water supply autlaak canditians, including selected stream,
<br />flaw farecasts, summary af snaw accumulatian to. date, and starage in larger reservairs,
<br />
<br />Prabability Farecasts
<br />
<br />Precipitatian and snawfall accum'ulatlan af knawn probability as determined byanalyslsaf past recards
<br />are utilized In the preparatian af prababllity runaff farecasts, The farecasts Include an evaluatian af the
<br />standard errar af the predictlan madel. The farecasts are presented at three levels af prabability as
<br />fallaws:
<br />
<br />1. Mast Probable - That runaff which is expected to. accur if precipitatian subsequent to. the date af
<br />farecast is median,
<br />
<br />2, Reasanable Maximum -That runaff which is expected to. accur if precipitatian subsequent to. the
<br />date af farecast is equal to. the amaunt which is exceeded an the average ance in ten years,
<br />
<br />3, Reasanable Minimum - That runaff which is expected to. accur if preclpitatlan subsequent to. the
<br />dates af farecast is equal to. the amaunt which is exceeded an the average nine aut af ten years,
<br />
<br />RUNOFF FORECASTS AT ALL POINTS ARE FOR FULL NATURAL OR UNIMPAIRED RUNOFF
<br />CORRECTED FOR EVAPORATION, UPSTREAM DIVERSIONS, AND ADJUSTED FOR OTHER HYDROLOG,
<br />IC CHANGES AS THEY ARE DEVELOPED, REFERENCE SHOULD BE MADE TO THE U,S, GEOLOGICAL
<br />SURVEY WATER SUPPLY PAPERS FOR DETAILED INFORMATION CONCERNING DIVERSIONS AND
<br />ADJUSTMENTS AT THE VARIOUS FORECAST POINTS,
<br />
|