HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE SEATTLE WA
210 PM PDT WED APR 9 2008
...WASHINGTON WATER SUPPLY OUTLOOK...
THE FORECASTS OF WATER SUPPLY FOR THE SPRING AND SUMMER IN
WASHINGTON ARE FOR NORMAL TO ABOVE NORMAL AMOUNTS FOR MOST
WASHINGTON RIVERS. FORECASTS WERE FOR HIGHER AMOUNTS THAN LAST
MONTH FOR MOST RIVERS...UP TO 10 PERCENT ON THE EAST SIDE AND UP TO
5 PERCENT ON THE WEST SIDE.
PRECIPITATION SUMMARY
---------------------
PRECIPITATION IN WASHINGTON DURING THE MONTH OF MARCH VARIED FROM
MUCH BELOW NORMAL TO ABOVE NORMAL ON BOTH WEST AND EAST SIDES.
FOR WESTERN WASHINGTON...THE PERCENTAGE OF NORMAL PRECIPITATION
RANGED FROM 80 FOR THE OLYMPICS TO 127 FOR THE NORTHWEST INTERIOR.
FOR EASTERN WASHINGTON...THE PERCENTAGE OF NORMAL PRECIPITATION
RANGED FROM ONLY 46 FOR THE EAST SLOPES OF THE CASCADES TO 111 FOR
THE NORTHEAST REGION.
SNOWPACK SUMMARY
----------------
THE SNOWPACK WAS ABOVE NORMAL FOR MOST OF WASHINGTON. AS OF APRIL
2...THE WATER CONTENT OF THE MOUNTAIN SNOWPACK IN THE BASINS THAT
FEED THE MAJOR RIVERS EAST OF THE CASCADES CREST RANGED FROM 90 TO
146 PERCENT OF NORMAL. WEST OF THE CASCADES...THE WATER CONTENT OF
THE SNOWPACK RANGED FROM 111 TO 179 PERCENT OF NORMAL.
SNOW DEPTH LEVELS FROM THE NORTHWEST AVALANCHE CENTER RANGED FROM
113 TO 179 PERCENT OF NORMAL AS OF APRIL 1.
STREAMFLOWS SUMMARY
------------------
STREAMFLOWS WERE NEAR TO BELOW NORMAL FOR MOST OF WASHINGTON RIVERS
AS OF APRIL 1. SOME AREAS HAD BELOW NORMAL FLOWS WHERE COOLER
TEMPERATURES HAD SLOWED MELT WATER AND KEPT IT OUT OF RUNOFF.
WEATHER OUTLOOK
---------------
THE OUTLOOK FOR APRIL AND BEYOND...THE OUTLOOK FOR THE MONTH OF
APRIL IS FOR A SLIGHTLY GREATER CHANCE OF ABOVE NORMAL
PRECIPITATION. THE OUTLOOK FOR THE PERIOD APRIL THROUGH JUNE IS FOR
EQUAL CHANCES OF BELOW...ABOVE...OR NORMAL PRECIPITATION.
WATER SUPPLY OUTLOOK
--------------------
LONG RANGE HYDROLOGIC MODELS WERE FORECASTING NEAR NORMAL TO ABOVE
NORMAL RIVER FLOWS AND WATER SUPPLY FOR MOST RIVERS THROUGH THIS
SPRING AND SUMMER. THE EXCEPTIONS WERE FORECASTS FOR BELOW NORMAL
IN THE NORTH CENTRAL OKANOGAN REGION. THE FORECAST FOR THE COLUMBIA
RIVER AT THE DALLES WAS FOR 101 PERCENT OF NORMAL. THE FORECASTS FOR
EASTERN WASHINGTON RANGED FROM AROUND 85 TO NEARLY 130 PERCENT OF
NORMAL. THE METHOW AND SIMILKAMEEN RIVER BASINS HAD THE LOWEST
AMOUNT FORECAST AT 87 PERCENT OF NORMAL AND THE STREAMS IN THE
YAKIMA BASIN HAD THE HIGHEST AMOUNT FORECAST AT AROUND 125 TO 128
PERCENT OF NORMAL. WATER SUPPLY FORECASTS FOR WESTERN WASHINGTON
WERE AROUND 100 TO 125 PERCENT OF NORMAL. FORECASTS ASSUMED
CLIMATIC CONDITIONS DURING THE FORECAST PERIOD.
HERE ARE THE STREAM FLOW VOLUME FORECASTS FOR SPECIFIC RIVERS AND
SITES AS OF APRIL 7.
WATER SUPPLY FORECASTS
(IN THOUSANDS OF ACRE FEET)
RIVER AND GAUGING SITE PERIOD FORECAST NORMAL PERCENT
COLUMBIA RIVER
AT GRAND COULEE DAM JAN-JUL 61200 62900 97
APR-SEP 65200 63990 102
BELOW ROCK ISLAND DAM APR-SEP 67600 69540 98
NEAR THE DALLES JAN-JUL 101000 107300 94
APR-SEP 100000 98650 101
PEND OREILLE RIVER
PEND OREILLE LAKE INFLOW APR-SEP 14800 13910 106
COUER D'ALENE RIVER
COUER D'ALENE LAKE INFLOW APR-JUL 3070 2552 120
OKANOGAN RIVER
NEAR TONASKET APR-SEP 1550 1766 88
SIMILKAMEEN RIVER
NEAR NIGHTHAWK APR-JUL 1180 1350 87
CHELAN RIVER
LAKE CHELAN INFLOW APR-SEP 1140 1185 96
WENATCHEE RIVER
AT PESHASTIN APR-SEP 1750 1635 107
YAKIMA RIVER
NEAR PARKER APR-SEP 2320 1918 121
SNAKE RIVER
LOWER GRANITE RSVR INFLOW JAN-JUL 28000 30020 93
APR-JUL 23300 21550 108
SOUTH FORK WALLA WALLA RIVER
NEAR MILTON APR-JUL 61 53 115
SKAGIT RIVER
NEAR CONCRETE APR-SEP 6720 6365 106
COWLITZ RIVER
MAYFIELD RESERVOIR INFLOW APR-JUL 2100 1689 124
APR-SEP 2390 1922 124
AT CASTLE ROCK APR-SEP 3170 2639 120
DUNGENESS RIVER
NEAR SEQUIM APR-SEP 178 152 117
THESE FORECASTS ARE SELECTED FROM THOSE PREPARED BY: NATIONAL
WEATHER SERVICE...NATURAL RESOURCE CONSERVATION SERVICER...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
THE NEXT WATER SUPPLY OUTLOOK FOR WASHINGTON WILL BE ISSUED AROUND
MAY 7.
JBB
WEATHER.GOV/SEATTLE