Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 251600
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 AM PDT WED MAR 25 2015

.SYNOPSIS...RAIN TODAY WILL DECREASE THIS EVENING AS A WARM FRONT
MOVES NORTH TO BRITISH COLUMBIA. AN UPPER LEVEL RIDGE WILL BRING
WARM AND DRY CONDITIONS THURSDAY. A COLD FRONT WILL REACH THE AREA
FRIDAY EVENING. HIGH PRESSURE WILL BUILD OVER THE WEEKEND. ANOTHER
FRONT WILL ARRIVE EARLY NEXT WEEK.

&&

.SHORT TERM...A WARM FRONT IS OVER WESTERN WASHINGTON TODAY. THE
RAIN WILL TAPER OFF FROM THE S TONIGHT AS AN UPPER RIDGE BUILDS INTO
THE REGION. THERE MIGHT BE A FEW PATCHES OF LIGHT RAIN OR DRIZZLE
NEAR THE B.C. BORDER AT DAYBREAK BUT OTHERWISE THURSDAY WILL BE DRY
WITH INCREASING SUNSHINE BY AFTERNOON. THE RIDGE WILL SHIFT EAST
FRIDAY. A WEATHER SYSTEM COULD BRING RAIN TO THE NORTH COAST BY
MIDDAY FRIDAY BUT MOST OF WESTERN WA SHOULD NOT SEE PRECIP TIL
EVENING. THIS SYSTEM LOOKS PRETTY HEALTHY IN THE 12Z NAM AND NOT
NEARLY AS SPLITTY AND DISORGANIZED AS IT LOOKED IN YESTERDAYS
SOLUTIONS. I HAVE NOT SEEN THE 12Z GFS YET...BUT THE 06Z GFS WAS
MUCH WEAKER WITH THIS SYSTEM THAN THIS 12Z NAM SOLN. THE FORECAST
FOR SATURDAY ALSO LOOKS DIFFERENT IN THE NEW NAM...IT HAS A WARM
FRONT SPREADING RAIN TO THE WA COAST SATURDAY AFTERNOON...LEAVING
THE PROSPECT OF A DRY UPPER RIDGE FOR THE WEEKEND IN DOUBT.

.LONG TERM...THE GFS...ECMWF AND CANADIAN ALL MAINTAIN A BROAD FLAT
UPPER LEVEL RIDGE OVER W WA THROUGH THIS WEEKEND. FLOW ALOFT WILL BE
WESTERLY. ALL MODELS SHOW A WARM FRONT MOVING NE ACROSS VANCOUVER
ISLAND SATURDAY AFTERNOON...BRUSHING THE WA COAST AND N INTERIOR IN
THE PROCESS. THE REST OF W WA SHOULD REMAIN DRY WITH EVEN PARTLY
SUNNY SKIES AT TIMES. THE WEAK WARM ADVECTION BRUSHING THE NW PART
WILL CONTINUE THROUGH SUNDAY. ANY RAIN THAT FALLS SHOULD BE
LIGHT...BUT WITH GOOD MODELS CONSENSUS...A CHANCE OF RAIN HAD TO BE
PUT BACK IN THE FORECAST. THE MODELS ARE IN LOOSER AGREEMENT FOR
MONDAY AND TUESDAY WHEN THE ASSOCIATED COLD FRONT WILL MOVE ACROSS W
WA. KAM

&&

.HYDROLOGY...FLOODING IS UNLIKELY THE NEXT 7 DAYS.

&&

.AVIATION...A WARM FRONT WILL LIFT NORTH THROUGH WESTERN WA TODAY
FOR CONTINUED LIGHT RAIN. THE AIR MASS IS MOIST AND STABLE. THE FLOW
ALOFT IS WESTERLY. RAIN WILL TAPER OFF THIS EVENING AS THIS FRONT
MOVES NORTH INTO BRITISH COLUMBIA. MVFR CIGS WILL LIKELY PERSIST
THROUGH MUCH OF THE DAY. 33

KSEA...MVFR CIGS TODAY WITH -RA. SURFACE WINDS WILL REMAIN SOUTHERLY
TO 12 KT. RAIN ENDING BY 06Z BUT MVFR CONDITIONS WILL CONTINUE
THROUGH THU MORNING. 33

&&

.MARINE...A WARM FRONT WILL LIFT NORTH THROUGH WESTERN WA TODAY WITH
MODERATE S/SE WINDS ACROSS THE AREA. A GALE WARNING IS UP FOR THE
EASTERN STRAIT OF JUAN DE FUCA. SMALL CRAFT ADVISORIES ARE IN EFFECT
FOR ALL OTHER WATERS EXCEPT THE CENTRAL STRAIT OF JUAN DE FUCA.
WINDS WILL EASE EASE LATE THIS AFTERNOON AND EVENING AS THIS FRONT
MOVES NORTH INTO BRITISH COLUMBIA. WEAK HIGH PRESSURE WILL MOVE OVER
THE AREA TONIGHT AND THURSDAY FOR GENERALLY LIGHT WINDS. A COLD
FRONT WILL CROSS THE REGION FRIDAY AFTERNOON OR EVENING. ONSHORE
FLOW WILL INCREASE BEHIND THE FRONT FRI NIGHT...SMALL CRAFT ADVISORY
WINDS ARE LIKELY THROUGH THE STRAIT OF JUAN DE FUCA. HIGH PRESSURE
WILL REBUILD OVER THE AREA THIS WEEKEND.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...GALE WARNING EAST STRAIT OF JUAN DE FUCA.
     SMALL CRAFT ADVISORY ALL WATERS EXCEPT CENTRAL STRAIT.

&&

$$

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML







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