Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 242205
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
305 PM PDT THU APR 24 2014

.SYNOPSIS...SHOWERS WILL CONTINUE ACROSS WESTERN WASHINGTON THIS
EVENING. AN UPPER LEVEL LOW WILL MOVE INLAND ON FRIDAY FOR ISOLATED
TO SCATTERED SHOWERS. A FRONTAL SYSTEM WILL BRING ANOTHER ROUND OF
RAINY WEATHER SATURDAY NIGHT INTO SUNDAY. AN UPPER LEVEL RIDGE WILL
BRING WARMER AND DRIER WEATHER TUESDAY ONWARDS.

&&

.SHORT TERM...EXPECT SCATTERED SHOWERS ACROSS WESTERN WASHINGTON
THIS EVENING AS AN UPPER LEVEL TROUGH AXIS SWINGS THROUGH THE AREA.
THERE IS A SLIGHT CHANCE OF THUNDERSTORMS BETWEEN SEATTLE AND
BELLINGHAM...THERE WERE A FEW STRIKES NEAR GRANITE FALLS EARLIER.
SHOWERS WILL TAPER OFF AFTER MIDNIGHT TONIGHT.

AN UPPER LEVEL LOW WILL MOVE OVERHEAD ON FRIDAY KEEPING THE AIR MASS
COOL AND UNSTABLE. EXPECT SCATTERED SHOWERS ONCE AGAIN...MAINLY
DURING THE AFTERNOON. THIS LOW WILL WEAKEN FRIDAY NIGHT WITH SHOWERS
ENDING.

SATURDAY WILL BE MAINLY DRY...THEN WET WEATHER WILL RETURN SATURDAY
NIGHT AS THE NEXT COLD FRONT ARRIVES. THE GFS SHOWS THE FRONT ALONG
THE COAST BY 06Z...WITH PRECIP SPREADING INLAND OVERNIGHT. SHOWERS
ARE LIKELY ON SUNDAY WITH ONSHORE FLOW AND ZONAL FLOW ALOFT. TEMPS
WILL BE A FEW DEGREES COOLER WITH HIGHS IN THE LOWER 50S.

.LONG TERM...A WEAK WARM FRONT MAY CLIP WESTERN WASHINGTON ON MONDAY
FOR A CHANCE OF RAIN. CONFIDENCE IS LOW AND ANY PRECIP LOOKS LIGHT
AT THIS POINT. MODELS THEN BUILD A RIDGE OVER THE PAC NW TUE AND
WED FOR A DRY AND WARM PERIOD OF WEATHER. THE LOW LEVEL FLOW WILL
FLIP OFFSHORE WITH HIGHS IN THE 60S TO 70S...ALONG WITH MOSTLY SUNNY
SKIES. THE CURRENT FORECAST IS NUDGED TOWARD THE ECMWF AND CANADIAN
MODELS WHICH BOTH KEEP HIGH PRES OVER THE REGION THROUGH NEXT
WEEKEND. THE GFS BREAKS DOWN THE RIDGE ON THURSDAY BUT THIS SOLUTION
LOOKS LIKE AN OUTLIER FOR NOW. 33

&&

.HYDROLOGY...RIVER FLOODING REMAINS UNLIKELY FOR THE NEXT 7 DAYS.

THE EXCEPTION REMAINS THE NORTH FORK OF THE STILLAGUAMISH RIVER EAST
OF THE SR 530 LANDSLIDE NEAR OSO WHERE A FLOOD WARNING REMAINS IN
EFFECT UNTIL FURTHER NOTICE. FLOODING CONTINUES FOR THIS RIVER AS A
RESULT OF WATER POOLED BEHIND THE DEBRIS DAM THAT PARTIALLY BLOCKS
THE RIVER.

AT 3 PM...THE NORTH FORK OF THE STILLAGUAMISH NEAR ARLINGTON WAS AT
6.1 FT...OR 5330 CFS. THE NORTH FORK OF THE STILLAGUAMISH RIVER NEAR
OSO WAS AT 217.93 FT AT 3250 CFS. THE POOL EAST OF THE SLIDE WAS
283.36 FT THIS MORNING. THE RIVER HAS CRESTED FROM HEAVY RAINS LAST
NIGHT AND WILL CONTINUE TO RECEDE.

EXPECT SCATTERED SHOWERS IN THE REGION TONIGHT AND FRIDAY WITH
RAINFALL AMOUNTS UP TO 0.25 INCHES. A COLD FRONT SATURDAY NIGHT MAY
PRODUCE ANOTHER 0.50 INCHES. OTHERWISE DRY WEATHER IS FORECAST
THROUGHOUT MUCH OF NEXT WEEK.

&&

.AVIATION...MODERATE SOUTHERLY FLOW ALOFT TONIGHT WILL BECOME LIGHT
FRIDAY AS AN UPPER LEVEL TROUGH MOVES OVER THE AREA. THE AIR MASS IS
MOIST AND UNSTABLE WITH SCATTERED SHOWERS. SATELLITE IMAGERY SHOWS A
FEW BREAKS IN THE CLOUDS. THIS PATTERN WILL CONTINUE THIS EVENING
BUT THE AIR MASS WILL STABILIZE OVERNIGHT AND THERE WILL BE SOME
CLEARING. GUSTY SOUTHWEST WINDS WILL EASE THIS EVENING. FRIDAY WILL
BE SIMILAR BUT WITHOUT THE GUSTY WINDS OF TODAY.

CEILINGS ARE MOSTLY VFR BUT MVFR 2-3K FT CEILINGS ARE POSSIBLE IN
SHOWERS. THERE COULD BE AN ISOLATED THUNDERSTORM THIS AFTERNOON.

KSEA...MOSTLY VFR CEILINGS WITH A CHANCE OF A BRIEF FALL TO MVFR
THIS EVENING. SOME CLEARING LATER THIS EVENING. GUSTY SOUTHWEST
WIND 10G20KT EASING TONIGHT. CHB

&&

.MARINE...SMALL CRAFT ADVISORIES REMAIN IN EFFECT OVER ALL WATERS AS
GUSTY SOUTHWEST WINDS 15-30 KT CONTINUE. WINDS WILL EASE THIS EVENING
AND MOST AREAS SHOULD BE BELOW 20 KT BY 06Z TONIGHT.

AFTER A LULL IN THE ACTION FRIDAY...ANOTHER FRONT WILL SPREAD SMALL
CRAFT ADVISORY STRENGTH WINDS OVER THE AREA SATURDAY NIGHT. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNING REMAINS IN EFFECT FOR THE NORTH FORK OF THE
     STILLAGUAMISH RIVER EAST OF THE SR 530 LANDSLIDE.

PZ...SMALL CRAFT ADVISORY ALL WATERS.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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