Note that if drought conditions are not being experienced, or in the case of river flooding or heavy rain, this statement may be used to indicate river flows or flood potential.
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WAC009-027-029-031-033-035-041-045-053-055-057-061-067-073-282300-
WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE SEATTLE WA
1136 PM PST SUN MAR 7 2010
...WASHINGTON WATER SUPPLY OUTLOOK...
THE FORECASTS OF WATER SUPPLY FOR THE SUMMER IN WASHINGTON WERE FOR
MUCH BELOW NORMAL AMOUNTS FOR MOST WASHINGTON RIVERS. THE EXCEPTION
WAS FOR RIVERS ON THE OLYMPIC PENINSULA WHICH WERE FORECAST TO BE
NEAR NORMAL. THE SPRING THROUGH SUMMER FORECAST FOR THE COLUMBIA
RIVER AT THE DALLES WAS FOR 67 PERCENT OF NORMAL.
PRECIPITATION SUMMARY
---------------------
FEBRUARY RAINFALL ACROSS WASHINGTON WAS BELOW NORMAL FOR MUCH OF THE
STATE. ONLY OKANOGAN AND THE CENTRAL BASIN WERE ABOVE NORMAL.
FOR WESTERN WASHINGTON...THE PERCENTAGE OF NORMAL PRECIPITATION
RANGED FROM 50 FOR THE CASCADES TO 84 FOR THE NORTHWEST INTERIOR.
FOR EASTERN WASHINGTON...THE PERCENTAGE OF NORMAL PRECIPITATION
RANGED WIDELY FROM 51 FOR THE PALOUSE AND BLUE MOUNTAINS TO
148 FOR THE OKANOGAN REGION.
SNOWPACK SUMMARY
----------------
THE SNOWPACK WAS GENERALLY MUCH BELOW NORMAL FOR MOST OF WASHINGTON
AS OF MARCH 7. THE WATER CONTENT OF THE MOUNTAIN SNOWPACK IN THE
BASINS THAT FEED THE MAJOR RIVERS EAST OF THE CASCADES CREST RANGED
FROM 50 TO 82 PERCENT OF NORMAL. WEST OF THE CASCADES...THE WATER
CONTENT OF THE SNOWPACK RANGED FROM 47 TO 65 PERCENT OF NORMAL.
HOWEVER THE OLYMPIC MOUNTAINS ARE NEAR NORMAL AT 95 PERCENT. THE
AMOUNT OF PRECIPITATION WAS BELOW NORMAL IN MOST AREAS...THUS
LEADING TO BELOW NORMAL SNOWPACK.
DATA FROM THE NORTHWEST WEATHER AND AVALANCHE CENTER AS OF MARCH 1
SHOWED THAT SNOW DEPTHS WERE 52 TO 109 PERCENT OF NORMAL.
STREAMFLOWS SUMMARY
-------------------
STREAMFLOWS WERE MUCH BELOW NORMAL TO NORMAL FOR MOST OF WESTERN
WASHINGTON AS OF MARCH 7. STATIONS THAT WERE MUCH BELOW NORMAL
OUTNUMBERED STATIONS THAT WERE NEAR NORMAL.
RESERVOIR STORAGE SUMMARY
-------------------------
STORAGE FOR RESERVOIRS AROUND THE STATE AVERAGED SLIGHTLY BELOW
NORMAL AS OF THE FIRST OF MARCH. STORAGE IN PERCENT OF AVERAGE FOR
RESERVOIRS RANGED FROM 60 TO 151. RESERVOIRS IN THE CASCADES HAD
THE GREATEST PERCENTAGE STORAGE WITH MANY REPORTING ABOVE NORMAL.
WEATHER OUTLOOK
---------------
THE OUTLOOK FOR MARCH AND BEYOND...THE OUTLOOK FOR MARCH IS BELOW
NORMAL PRECIPITATION. THE OUTLOOK FOR MARCH THROUGH MAY IS FOR
GREATER CHANCES OF BELOW NORMAL PRECIPITATION.
WATER SUPPLY OUTLOOK
--------------------
LONG RANGE HYDROLOGIC MODELS WERE FORECASTING MUCH BELOW NORMAL
RIVER FLOWS AND WATER SUPPLY FOR MOST RIVERS THROUGH THIS SPRING AND
SUMMER. THE FORECASTS FOR EASTERN WASHINGTON RANGED FROM AROUND 47
TO 76 PERCENT OF NORMAL. THE COUER D`ALENE RIVER BASIN HAD THE
LOWEST AMOUNT FORECAST AT 47 PERCENT OF NORMAL. THE MIDDLE COLUMBIA
RIVER HAD THE HIGHEST AMOUNT FORECAST AT 76 PERCENT OF NORMAL.
WATER SUPPLY FORECASTS FOR WESTERN WASHINGTON WERE FROM AROUND 75 TO
92 PERCENT OF NORMAL. FORECASTS ASSUMED 75 PERCENT OF NORMAL
PRECIPITATION FOR MARCH THEN CLIMATIC CONDITIONS DURING THE REST OF
THE FORECAST PERIOD.
HERE ARE THE STREAM FLOW VOLUME FORECASTS FOR SPECIFIC RIVERS AND
SITES AS OF MARCH 5.
WATER SUPPLY FORECASTS
(IN THOUSANDS OF ACRE FEET)
RIVER AND GAUGING SITE PERIOD FORECAST NORMAL PERCENT
COLUMBIA RIVER
AT GRAND COULEE DAM JAN-JUL 47300 62900 75
APR-SEP 48500 63990 76
BELOW ROCK ISLAND DAM APR-SEP 52900 69540 76
NEAR THE DALLES JAN-JUL 71800 107300 67
APR-SEP 65800 97300 67
PEND OREILLE RIVER
PEND OREILLE LAKE INFLOW APR-SEP 8590 13910 62
COUER D`ALENE RIVER
COUER D`ALENE LAKE INFLOW APR-JUL 365 2552 47
OKANOGAN RIVER
NEAR TONASKET APR-SEP 1190 1766 67
SIMILKAMEEN RIVER
NEAR NIGHTHAWK APR-JUL 860 1350 64
CHELAN RIVER
LAKE CHELAN INFLOW APR-SEP 850 1185 72
WENATCHEE RIVER
AT PESHASTIN APR-SEP 1110 1635 68
YAKIMA RIVER
NEAR PARKER APR-SEP 1210 1918 63
SNAKE RIVER
LOWER GRANITE RSVR INFLOW JAN-JUL 17000 30020 57
APR-JUL 12100 21550 56
SOUTH FORK WALLA WALLA RIVER
NEAR MILTON APR-JUL 38 53 72
SKAGIT RIVER
NEAR CONCRETE APR-SEP 4980 6365 78
COWLITZ RIVER
MAYFIELD RESERVOIR INFLOW APR-JUL 1270 1689 75
APR-SEP 1440 1922 75
AT CASTLE ROCK APR-SEP 2040 2639 77
DUNGENESS RIVER
NEAR SEQUIM APR-SEP 140 152 92
THESE FORECASTS ARE SELECTED FROM THOSE PREPARED BY: NATIONAL
WEATHER SERVICE...NATURAL RESOURCE CONSERVATION SERVICE...AND B.C.
HYDRO AND POWER AUTHORITY. FOR VARIOUS PROJECT INFLOWS...THE
FORECASTS HAVE BEEN COORDINATED WITH THE U.S. ARMY CORP OF ENGINEERS
AND THE U.S. BUREAU OF RECLAMATION.
FOR FURTHER DETAILS ON THE WATER SUPPLY FORECAST VISIT
HTTP://WWW.NWRFC.NOAA.GOV/WATER_SUPPLY/WS_FCST.CGI (LOWER CASE).
THE NEXT WATER SUPPLY OUTLOOK FOR WASHINGTON WILL BE ISSUED AROUND
APRIL 5.
$$
JBB
WEATHER.GOV/SEATTLE
