HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE SEATTLE WA
330 PM PST TUE FEB 8 2005
WASHINGTON WATER SUPPLY OUTLOOK
PREDOMINATELY DRY AND WARM CONDITIONS HAVE BEEN IN PLACE SINCE THE
FIRST OF THIS SEASON RESULTING IN BELOW NORMAL PRECIPITATION AND
SNOWPACK. FORECASTS OF WATER SUPPLY FOR THE SPRING AND SUMMER ARE
FOR MUCH BELOW NORMAL AMOUNTS.
PRECIPITATION SUMMARY
---------------------
RAINFALL IN WASHINGTON DURING THIS MONTH WAS BELOW NORMAL TO NEAR
NORMAL WITH THE EXCEPTION OF THE SOUTHEAST CORNER OF PALOUSE AND BLUE
MOUNTAINS WHICH WERE MUCH BELOW NORMAL.
FOR WESTERN WASHINGTON...THE PERCENTAGE OF NORMAL PRECIPITATION
RANGED FROM 73 FOR THE OLYMPICS TO 101 FOR THE COAST. THE GREATEST
AMOUNT OF PRECIPITATION RECORDED AT CLIMATE STATIONS FOR THE
MOUNTAINS AND FOOTHILLS...COASTS...AND INTERIOR LOWLANDS WAS 18.05
INCHES AT FORKS...21.09 INCHES AT CLEARWATER...AND 10.24 INCHES AT
SHELTON RESPECTIVELY.
FOR EASTERN WASHINGTON...THE PERCENTAGE OF NORMAL PRECIPITATION
RANGED FROM JUST 33 FOR PALOUSE AND BLUE MOUNTAINS REGION TO 79 FOR
THE NORTHEAST REGION. THE GREATEST AMOUNT OF PRECIPITATION RECORDED
AT CLIMATE STATIONS FOR THE MOUNTAINS AND FOOTHILLS AND THE LOWLANDS
WAS 5.36 INCHES AT STEHEKIN AND 2.16 INCHES AT NEWPORT RESPECTIVELY.
THE TABLE BELOW GIVES PRECIPITATION FIGURES AS A PERCENT OF NORMAL
FOR REGIONS OF WASHINGTON. THE CURRENT WATER YEAR BEGAN 1 OCTOBER
2004 AND ENDS 30 SEPTEMBER 2005.
JAN WATER YEAR PAST 3 PAST 12
2005 TO DATE MONTHS MONTHS
WESTERN WASHINGTON
COAST 101 88 82 86
OLYMPICS 73 79 74 79
NORTHWEST INTERIOR 98 105 106 105
PUGET SOUND LOWLANDS 78 79 76 81
SOUTHWEST INTERIOR 79 69 60 79
WEST FOOTHILLS CASCADES 73 79 74 85
CASCADES 82 79 77 86
EASTERN WASHINGTON
EAST SLOPES CASCADES 75 68 58 79
OKANOGAN 78 75 59 86
CENTRAL BASIN 72 67 54 93
NORTHEAST 79 82 69 95
PALOUSE AND BLUE MOUNTAINS 33 57 53 74
SNOWPACK SUMMARY
----------------
THE SNOWPACK WAS MUCH BELOW NORMAL THROUGHOUT WASHINGTON. WARMER
AND DRIER THAN NORMAL WEATHER THIS FALL THROUGH WINTER HAS RESULTED
IN MUCH LESS SNOWFALL THIS SEASON THAN NORMAL. AS OF FEBRUARY 8...
THE WATER CONTENT OF THE MOUNTAIN SNOWPACK IN THE BASINS THAT FEED
THE MAJOR RIVERS EAST OF THE CASCADES CREST VARIED FROM 20 TO 49
PERCENT OF NORMAL. WEST OF THE CASCADES...THE WATER CONTENT OF THE
SNOWPACK RANGED FROM 15 TO 52 PERCENT OF NORMAL WITH MOST AROUND 25
PERCENT. THE AVERAGE DATE OF THE SEASONAL MAXIMUM WATER CONTENT OF
THE SNOWPACK IS APRIL 1.
WEATHER OUTLOOK
---------------
THE OUTLOOK FOR FEBRUARY AND BEYOND...FEBRUARY WILL HAVE EQUAL
CHANCES OF ABOVE OR BELOW NORMAL PRECIPITATION. THE OUTLOOK FOR
FEBRUARY THROUGH APRIL IS FOR GREATER CHANCE OF BELOW NORMAL
PRECIPITATION.
WATER SUPPLY OUTLOOK
--------------------
LOWER THAN NORMAL PRECIPITATION CONTINUES FOR THE SEASON. MORE
IMPORTANTLY...THE WARMER THAN NORMAL TEMPERATURES HAVE MEANT LESS
SNOW FALL AND EVEN HEAVY RAIN IN THE MOUNTAINS WASHING AWAY MUCH OF
THE SNOW THAT HAD FALLEN. THUS THE FORECASTS OF WATER SUPPLY ARE
FOR MUCH BELOW NORMAL AMOUNTS EXCEPT FOR THE UPPER REACHES OF THE
COLUMBIA RIVER IN THE NORTH. LONG RANGE HYDROLOGIC MODELS ARE
FORECASTING BELOW NORMAL RIVER FLOWS AND WATER SUPPLY FOR MOST
RIVERS THROUGH THE SPRING AND SUMMER IN THE RANGE OF AROUND 55 TO 90
PERCENT WITH MOST AROUND 60 TO 70 PERCENT. IN EASTERN
WASHINGTON...THE LOWER SNAKE RIVER BASINS AND THE STREAMS OFF THE
EASTERN SLOPES OF THE CASCADES HAD THE LOWEST AMOUNT FORECAST AT
AROUND 60 PERCENT OF NORMAL. THE UPPER COLUMBIA HAD THE HIGHEST
AMOUNT FORECAST AT AROUND 90 PERCENT OF NORMAL. WATER SUPPLY
FORECASTS FOR WESTERN WASHINGTON WERE AROUND 65 PERCENT OF NORMAL.
FORECASTS ASSUME 70 PERCENT OF NORMAL RAINFALL FOR FEBRUARY THEN
NORMAL CLIMATIC CONDITIONS DURING THE REST OF THE FORECAST PERIOD.
HERE ARE STREAM FLOW VOLUME FORECASTS FOR SPECIFIC RIVERS AND SITES
AS OF FEBRUARY 8.
WATER SUPPLY FORECASTS
(IN THOUSANDS OF ACRE FEET)
RIVER AND GAUGING SITE PERIOD FORECAST NORMAL PERCENT
COLUMBIA RIVER
AT GRAND COULEE DAM JAN-JUL 57200 62900 91
APR-SEP 56700 63990 89
BELOW ROCK ISLAND DAM APR-SEP 60900 69540 88
NEAR THE DALLES JAN-JUL 82400 107300 77
APR-SEP 73300 98650 74
PEND OREILLE RIVER
PEND OREILLE LAKE INFLOW APR-SEP 8920 13910 64
COUER D'ALENE RIVER
COUER D'ALENE LAKE INFLOW APR-JUL 1470 2552 58
OKANOGAN RIVER
NEAR TONASKET APR-SEP 1230 1766 70
SIMILKAMEEN RIVER
NEAR NIGHTHAWK APR-JUL 835 1350 62
CHELAN RIVER
LAKE CHELAN INFLOW APR-SEP 705 1185 59
WENATCHEE RIVER
AT PESHASTIN APR-SEP 990 1635 61
YAKIMA RIVER
NEAR PARKER APR-SEP 1050 1918 55
SNAKE RIVER
LOWER GRANITE RSVR INFLOW JAN-JUL 18000 30020 60
APR-JUL 12700 21550 59
SOUTH FORK WALLA WALLA RIVER
NEAR MILTON APR-JUL 39 53 74
SKAGIT RIVER
NEAR CONCRETE APR-SEP 4080 6365 64
COWLITZ RIVER
MAYFIELD RESERVOIR INFLOW APR-JUL 1080 1689 64
APR-SEP 1230 1922 64
AT CASTLE ROCK APR-SEP 1660 2639 63
ALL VOLUME NORMALS ARE FOR THE PERIOD 1971 THROUGH 2000.
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/water_supply.cgi
THE NEXT WATER SUPPLY OUTLOOK FOR WASHINGTON WILL BE ISSUED AROUND MARCH 8.
JBB