Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 020404
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
905 PM PDT WED OCT 1 2014

.SYNOPSIS...A WEAK RIDGE WILL PROVIDE DRY WEATHER THROUGH FRIDAY
WITH SOME AFTERNOON SUNSHINE EACH DAY. THE SOUTH INTERIOR WILL
LIKELY GET SOME LATE NIGHT AND MORNING FOG. A WEAK FRONT COULD BRING
SOME RAIN FRIDAY NIGHT THROUGH MONDAY BUT MOSTLY CONFINED TO THE
COAST...NORTH INTERIOR...AND MOUNTAINS. THERE WILL BE A LITTLE
BETTER CHANCE OF LIGHT RAIN TUESDAY AND WEDNESDAY AS A WEAK FRONT
DRIFTS THROUGH WESTERN WASHINGTON.

&&

.SHORT TERM...EXPECT DRY WEATHER ACROSS WESTERN WA TONIGHT THROUGH
THURSDAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE NE PAC. PATCHY FOG
WILL DEVELOP OVERNIGHT WITH LOWS DOWN TO THE MID 40S TO LOWER 50S. A
WEAK WARM FRONT WILL BRING A FEW MID/HIGH CLOUDS TO THE AREA ON
FRI...BUT THE BULK OF THE PRECIP IS DEFLECTED NORTH INTO B.C. HIGH
TEMPS WILL BE CLOSE TO NORMAL.

THE RIDGE WILL WEAKEN/FLATTEN OVER WA ON FRI...BUT WE ARE STILL
LOOKING DRY. THEN FRI NIGHT INTO SAT THE WEAK BAROCLINIC ZONE WILL
SLOWLY SHIFT S FROM B.C. INTO WESTERN WA BRINGING A LITTLE LIGHT
RAIN. MODELS SHOW LIGHT RAIN MAINLY AFFECTING THE COAST AND
MOUNTAINS. 33

.LONG TERM...PREVIOUS DISCUSSION...EXTENDED MODELS ARE IN SOMEWHAT
BETTER AGREEMENT TODAY NOT TO SAY THEY WON`T FLIP FLOP AGAIN IN
SUBSEQUENT RUNS. THE 12Z ECMWF/18Z GFS BOTH SHOW A STRONGER RIDGE
NOW FOR SUNDAY INTO MONDAY KEEPING PRECIPITATION TO THE N. KEPT SOME
LOW POPS OVER THE COAST AND MOUNTAINS GIVEN THE LACK OF CONTINUITY
BETWEEN MODEL RUNS. IF THE RIDGE MAINTAINS THE DRY WEATHER THEN SOME
FOG SHOULD BE EXPECTED ACROSS SOME LOWLAND AREAS...ESPECIALLY TO THE
S.

BOTH THE GFS/ECMWF DRAG THE REMNANTS OF A FRONT INTO THE AREA ON
TUESDAY BUT SHOW ONLY LIGHT QPF. SINCE MODELS AGREE...THE TUESDAY
THROUGH WEDNESDAY PERIOD LOOKS LIKE THE MOST BEST SHOT OF BRINGING
SOME PRECIPITATION INTO THE AREA. CHANCE POPS ARE INDICATED IN THE
FORECAST. MERCER

&&

.AVIATION...MODERATE NORTHWEST FLOW ALOFT WILL CONTINUE OVER
WASHINGTON TONIGHT AND THURSDAY. A WEAK WARM FRONT WILL BRUSH THE
FAR NORTHWEST PART OF WESTERN WASHINGTON LATE TONIGHT AND FRIDAY. AT
THE SURFACE MODERATE ONSHORE TONIGHT WILL WEAKEN THURSDAY.

CLOUDS COVER THE NORTHERN PART OF THE STATE WITH CEILINGS 5K-8K FT
AND HIGHER LEVELS ABOVE. SOUTHERN AREAS ARE MAINLY CLEAR...WHICH
WILL ALLOW LOW STRATUS AND FOG TO FORM LATER TONIGHT. AIR MASS IS
STABLE.

KSEA...VFR CONDITIONS THROUGH THIS EVENING. IFR CONDITIONS FROM
STRATUS AND FOG ARE FORECAST 12Z-18Z. CHB

&&

.MARINE...A SURFACE RIDGE OFFSHORE WILL MOVE INLAND TONIGHT AS A
WARM FRONT OFFSHORE HEADS TOWARD VANCOUVER ISLAND. WEAK ONSHORE FLOW
WILL CONTINUE THROUGH THIS EVENING WITH MARGINAL SMALL CRAFT
ADVISORY WINDS IN THE CENTRAL AND EAST STRAIT OF JUAN DE FUCA. THESE
SHOULD END BY MIDNIGHT OR SO.

THE SURFACE RIDGE WILL SIT OVER WESTERN WASHINGTON THURSDAY AND
FRIDAY FOR A PERIOD OF WEAK OFFSHORE FLOW. A FRONTAL ZONE WILL
REMAIN NORTH OF THE AREA...OVER THE CENTRAL BRITISH COLUMBIA COAST.
ON FRIDAY NIGHT AND SATURDAY THE WEAKENING FRONT WILL FINALLY MOVE
SOUTH OVER WESTERN WASHINGTON. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EASTERN STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION AT
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