Flood Potential Outlook
Issued by NWS Seattle/Tacoma, WA

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WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE SEATTLE WA
235 PM PDT WED JUN 11 2014

...WESTERN WASHINGTON WATER SUPPLY...

OVERVIEW: THE EARLY OUTLOOK FORECASTS OF WATER SUPPLY FOR THE SUMMER
IN WESTERN WASHINGTON ARE FOR NEAR TO BELOW NORMAL NORMAL VOLUMES
FOR WESTERN WASHINGTON RIVERS.

PRECIPITATION SUMMARY
---------------------

MAY BROUGHT NEAR TO ABOVE NORMAL PRECIPITATION FOR THE WESTERN HALF
OF WASHINGTON STATE. HOWEVER...THE EASTERN HALF SAW BELOW NORMAL
PRECIPITATION FOR THE MONTH. FOR THE WATER YEAR...MOST OF THE
WESTERN HALF OF THE STATE IS NEAR NORMAL FOR PRECIPITATION WHILE
BELOW NORMAL PRECIPITATION PERSISTS FOR MOST OF THE EASTERN HALF.

IN WESTERN WASHINGTON...THE MONTHLY PERCENTAGE OF NORMAL FOR
PRECIPITATION RANGED FROM 106 PERCENT IN THE OLYMPIC MOUNTAINS TO
170 PERCENT IN THE NORTHWEST INTERIOR. THE GREATEST AMOUNT OF
PRECIPITATION AT THE CLIMATE STATIONS FOR THE MOUNTAINS...COAST...
AND INTERIOR LOWLANDS WAS 8.25 INCHES AT CEDAR LAKE IN THE WESTERN
SLOPES OF THE CASCADES...6.38 INCHES AT ABERDEEN...AND 7.20 INCHES
AT GRAYS RIVER IN THE SOUTHWEST INTERIOR.


SNOWPACK CONDITIONS
-------------------

THE SNOWPACK WAS ABOVE NORMAL FOR THE SOUTH AND NORTH PUGET SOUND
BASINS AND BELOW NORMAL FOR THE CENTRAL PUGET SOUND AND OLYMPIC
BASINS AS OF JUNE 11. THE WATER CONTENT OF THE MOUNTAIN SNOWPACK IN
THE BASINS THAT FEED THE MAJOR RIVERS WEST OF THE CASCADES RANGED
FROM 48 PERCENT OF NORMAL FOR THE OLYMPICS TO 161 PERCENT OF NORMAL
FOR THE NORTH PUGET SOUND.

STREAMFLOWS SUMMARY
-------------------

WESTERN WASHINGTON RIVERS WERE NORMAL TO BELOW NORMAL FOR MAY.


RESERVOIR STORAGE SUMMARY
-------------------------

THERE WAS JUST ONE REPORT OF STORAGE FOR MAJOR RESERVOIRS AROUND THE
WESTERN WASHINGTON FOR THE END OF MAY. ON THE SKAGIT RIVER...ROSS
STORAGE WAS 75 PERCENT OF AVERAGE.


WEATHER OUTLOOK
---------------

THE OUTLOOK FOR THE REST OF JUNE AND BEYOND...FOR THE NEXT TWO WEEKS
THE OUTLOOK IS FOR NEAR NORMAL PRECIPITATION FOR NORTHERN WASHINGTON
AND BELOW NORMAL FOR SOUTHERN WASHINGTON. THE THREE MONTH OUTLOOK
FROM JULY TO SEPTEMBER CALLS FOR EQUAL CHANCES OF
NORMAL...ABOVE...OR BELOW NORMAL PRECIPITATION FOR WASHINGTON.

WATER SUPPLY OUTLOOK
--------------------

LONG RANGE HYDROLOGIC MODELS ARE FORECASTING NEAR TO BELOW NORMAL
RIVER FLOWS AND WATER SUPPLY FOR MOST RIVERS THROUGH THIS LATE
SPRING AND SUMMER. WATER SUPPLY FORECASTS FOR WESTERN WASHINGTON
RANGE FROM A LOW OF 51 PERCENT FOR THE SULTAN RIVER TO 92 PERCENT OF
NORMAL FOR THE COWLITZ RIVER. WATER SUPPLY FORECASTS THAT INCLUDE
REGULATION ARE USED FOR LOCATIONS WHERE FORECASTS ARE LISTED BELOW
AS REGULATED...FOR ALL OTHER LOCATIONS FORECASTS ARE FOR NATURAL
VOLUMES.

HERE ARE THE STREAM FLOW VOLUME FORECASTS FOR SPECIFIC RIVERS AND
SITES AS OF JUNE 10

                           WATER SUPPLY FORECASTS
                  NATURAL FLOW UNLESS OTHERWISE SPECIFIED
                        (IN THOUSANDS OF ACRE FEET)

RIVER AND GAUGING SITE            PERIOD   FORECAST   NORMAL  PERCENT

SKAGIT RIVER
   NEAR CONCRETE (REGULATED)      JUN-SEP      3313     3773      88

BAKER RIVER
   UPPER BAKER RESERVOIR INFLOW   JUN-SEP       459      508      90

SULTAN RIVER
   SPADA LAKE INFLOW              JUN-SEP        50       98      51

TOLT RIVER
   TOLT RESERVOIR INFLOW          JUN-SEP        11       24      48

CEDAR RIVER
   CHESTER MORSE LAKE INFLOW      JUN-SEP        27       45      61

NISQUALLY RIVER
   ALDER RESERVOIR INFLOW         JUN-SEP       129      182      71

COWLITZ RIVER
   MAYFIELD RESERVOIR (REGULATED) JUN-SEP       637      696      92

ELWHA RIVER
   MCDONALD BRIDGE                JUN-SEP       183      311      59

DUNGENESS RIVER
   NEAR SEQUIM                    APR-SEP       124      145      86

WYNOOCHEE RIVER
   WYNOOCHEE DAM INFLOW           JUN-SEP        31       39      80

N.F. SKOKOMISH RIVER
   CUSHMAN DAM INFLOW             JUN-SEP        85      133      64


SNOW MELT CLIMATOLOGY:

RIVERS WEST OF THE CASCADES CREST USUALLY REACH THEIR HIGHEST PEAK
FLOWS DURING THE WINTER SEASON. THE VAST MAJORITY OF RIVER FLOODING
IN WESTERN WASHINGTON...AND ALMOST ALL MAJOR FLOODS...OCCUR BETWEEN
OCTOBER AND MARCH. HEAVY RAINFALL...RATHER THAN SNOW MELT...IS THE
PRIMARY CAUSE OF THESE EVENTS.

THE HISTORICAL RECORD DOES NOT SHOW MAJOR FLOODING IN WESTERN
WASHINGTON DURING THE PERIOD WHEN THE MOUNTAIN SNOWPACK RUNS OFF.
THE RUNOFF FROM SNOW MELT...EVEN DURING UNUSUALLY HOT WEATHER...IS
SMALL COMPARED TO THE RUNOFF DURING HEAVY WINTER RAINS. THIS IS TRUE
REGARDLESS OF THE SIZE OF THE MOUNTAIN SNOWPACK. RARELY...UNDER JUST
THE RIGHT CONDITIONS OF GREATER THAN NORMAL SNOW PACK...GREATER
COVERAGE TO LOWER ELEVATIONS...AND NEAR RECORD WARM TEMPERATURES...
RIVER FLOWS MIGHT RISE TO NEAR MINOR FLOOD STAGE.

WHILE FLOOD PRODUCING RAINFALL IS RARE AFTER MARCH...MODERATE TO
HEAVY RAIN IN SPRING OR SUMMER...WHILE RIVERS ARE SWOLLEN WITH SNOW
MELT RUNOFF...OCCASIONALLY DRIVE THE MOST FLOOD PRONE RIVERS ABOVE
FLOOD STAGE. TYPICALLY THESE ARE RIVERS SUCH AS THE SKOKOMISH AND
SNOQUALMIE. HEAVY RAIN IN THE SPRING OR SUMMER...WHEN ROSS LAKE IS
FULL...CAN ALSO CAUSE THE SKAGIT RIVER TO FLOOD. WHILE THESE FLOODS
ARE TYPICALLY MINOR COMPARED TO THE WINTER EVENTS...THEY SOMETIMES
CAUSE SUBSTANTIAL DAMAGE TO FARM CROPS.


SPRING AND SUMMER SNOW MELT PEAK FLOW FORECASTS:

HERE ARE THE LATEST SPRING AND SUMMER CREST FORECASTS FOR WESTERN
WASHINGTON RIVERS AS OF JUNE 11. STATISTICALLY THERE IS A 67 PERCENT
CHANCE THAT THE ACTUAL SPRING CREST WILL FALL WITHIN THE MOST LIKELY
RANGE.

RIVER AND SITE          FLOOD STAGE        MOST LIKELY RANGE OF
                                          THE SPRING/SUMMER CREST
SKAGIT RIVER
  NEAR MT. VERNON         28.0 FT            20.7 FT TO 20.8 FT

STILLAGUAMISH RIVER
  AT ARLINGTON            14.0 FT             3.6 FT TO 5.8 FT

SNOQUALMIE RIVER
  NEAR SNOQUALMIE        20000 CFS          6480 CFS TO 7150 CFS

PUYALLUP RIVER
  NEAR ORTING             4500 CFS          1875 CFS TO 1890 CFS

SF SKOKOMISH RIVER
  NEAR UNION                                 385 CFS TO 740 CFS


FORECASTS ARE SELECTED FROM THOSE PREPARED BY THE NWRFC.
FOR FURTHER DETAILS...GRAPHICS...AND STATISTICS REGARDING THE WATER
SUPPLY FORECASTS VISIT:
HTTP://WWW.NWRFC.NOAA.GOV/WS (LOWER CASE)
HTTP://WWW.NWRFC.NOAA.GOV/OUTLOOK (LOWER CASE)

FOR FURTHER DETAILS...GRAPHICS...AND STATISTICS REGARDING THE PEAK
FLOW FORECASTS VISIT:
HTTP://WWW.NWRFC.NOAA.GOV/PEAK (LOWER CASE)

THE NEXT WATER SUPPLY OUTLOOK FOR WESTERN WASHINGTON WILL BE ISSUED
AROUND THE WEEK OF JULY 6TH.

$$

WEATHER.GOV/SEATTLE

















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