Heavy Rain - Flood Watch...

posted Dec 10, 2010, 7:38 AM by smike@guemesfire.org   [ updated Dec 10, 2010, 7:49 AM ]
HEAVY RAIN IS COMING TO WESTERN WASHINGTON LATER THIS WEEKEND.  WEATHER MODELS DIFFER IN THE DETAILS BUT IS IS LIKELY THAT HEAVY
RAIN WILL BEGIN SATURDAY NIGHT...CONTINUE SUNDAY...AND END MONDAY.THE DURATION AND EXACT LOCATION OF THE HEAVIEST RAIN IS UNCERTAIN.  HOWEVER HEAVY RAIN IS LIKELY...AND IN AMOUNTS LIKELY TO CAUSE FLOODING ON AT LEAST SOME RIVERS.

THE NATIONAL WEATHER SERVICE IN SEATTLE HAS ISSUED A FLOOD WATCH FOR PORTIONS OF WA AND NORTHWEST WASHINGTON...INCLUDING THE FOLLOWING AREAS...IN WA...ADMIRALTY INLET AREA...CENTRAL COAST...EAST PUGET SOUND LOWLANDS...EASTERN STRAIT OF JUAN DE FUCA...EVERETT AND VICINITY...HOOD CANAL AREA...LOWER CHEHALIS VALLEY AREA...NORTH COAST...OLYMPICS...SEATTLE/BREMERTON AREA...SOUTHWEST INTERIOR...TACOMA AREA...WEST SLOPES CENTRAL CASCADES AND PASSES...WEST SLOPES NORTHERN CASCADES AND PASSES...WESTERN SKAGIT COUNTY...WESTERN STRAIT OF JUAN DE FUCA AND WESTERN WHATCOM COUNTY. IN NORTHWEST WASHINGTON...SAN JUAN COUNTY.

FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON...

A WARM AND MOIST WEATHER SYSTEM WILL MOVE INTO WESTERN WASHINGTON SATURDAY NIGHT. HEAVY RAIN WILL FALL AT TIMES. AT THIS TIME IT IS UNCERTAIN EXACTLY HOW MUCH RAIN WILL FALL AND WHAT PLACES WILL GET THE MOST RAIN. VARIOUS WEATHER MODELS BRING HEAVY RAIN TO DIFFERENT PLACES. THEREFORE THE FLOOD WATCH IS FOR EVERY COUNTY IN WESTERN WASHINGTON.

SOME RIVERS SEEM CERTAIN TO FLOOD...INCLUDING THE SKOKOMISH IN MASON COUNTY...THE TOLT IN KING COUNTY...AND THE PUYALLUP RIVER NEAR ORTING IN PIERCE COUNTY. THE FLOOD POTENTIAL ON OTHER RIVERS DEPENDS ON WHERE EXACTLY THE HEAVIEST RAIN FALLS.

RIVERS FACING AT LEAST A MODERATE THREAT OF FLOODING INCLUDE THE SATSOP AND CHEHALIS RIVERS IN LEWIS AND GRAYS HARBOR COUNTIES.   THE NOOKSACK SKAGIT STILLAGUAMISH AND SNOQUALMIE RIVERS FLOWING OFF THE NORTH CASCADES...AND THE DESCHUTES COWLITZ AND SKOOKUMCHUCK FLOWING OFF THE CENTRAL CASCADES.

EVEN SMALL STREAMS COULD OVERFLOW THEIR BANKS IF RAIN IS HEAVY ENOUGH. URBAN FLOODING WHERE DRAINAGE IS POOR IS ALSO A POSSIBILITY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLOOD WATCH MEANS CONDITIONS ARE FAVORABLE FOR FLOODING BUT FLOODING IS NOT IMMINENT OR OCCURRING. MONITOR THE LATEST FORECASTS FROM THE NATIONAL WEATHER SERVICE AND BE READY TO ACT QUICKLY IF FLOODING IS OBSERVED OR A WARNING IS ISSUED.
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