Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 141541
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
840 AM PDT TUE OCT 14 2014

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL MOVE OVER THE REGION THROUGH
WEDNESDAY. A FRONT WILL REACH WESTERN WASHINGTON THURSDAY NIGHT AND
FRIDAY. TEMPORARY HIGH PRESSURE WILL BUILD INTO THE AREA SATURDAY.

&&

.SHORT TERM...A SHOWERY WEATHER PATTERN WILL BE OVER THE REGION
THROUGH MIDWEEK. AN UPPER TROUGH JUST OFFSHORE WILL WEAKEN AND MOVES
INLAND OVER THE PACIFIC NORTHWEST. THE NAM SHOWS AN AREA OF PRECIP
DEVELOPING OVER NW OREGON THIS EVENING AND IT MOVES THROUGH THE
INTERIOR OF WESTERN WA OVERNIGHT...PERHAPS GIVING AROUND A HALF INCH
OF RAIN AS IT MOVES THROUGH THE AREA. THE GFS SHOWS THE BULK OF
PRECIP GOING INTO WRN OREGON OVERNIGHT AND KEEPS WRN WA IN LESS
ORGANIZED SPOTTY PRECIP. THE UPPER TROUGH FILLS AND THE REMNANTS
KICK THROUGH WRN WA WED FOLLOWED BY A BREAK IN THE SHOWERS WED NITE
AND PERHAPS MOST OF THURSDAY AHEAD OF THE NEXT FRONT.

.LONG TERM...A FRONT WILL SLOW AND GRADUALLY WEAKEN AS IT MOVES INTO
THE COASTAL WATERS THU NIGHT AND INLAND FRI. WHILE IT WILL BE
WEAKENING...THE FRONT WILL GIVE RAIN AND LOCALLY WINDY CONDITIONS TO
THE REGION. THE BEST CHANCE FOR WINDY CONDITIONS WILL BE ALONG THE
COAST AND OVER THE NORTH INTERIOR.

ANOTHER UPPER LEVEL RIDGE IS EXPECTED TO AMPLIFY OVER THE REGION
LATER SAT INTO SUN WHILE LOW LEVEL OFFSHORE FLOW DEVELOPS. THIS
AMPLIFICATION IN THE PATTERN IS A RESULT OF THE EXTRATROPICAL
REMAINS OF TYPHOON VONGFONG SWINGING INTO THE GULF OF ALASKA ALONG
145W. THE LATTER HALF OF SAT AND MOST OF SUN APPEARS THAT IT WILL BE
DRY OVER THE INTERIOR OF WESTERN WASHINGTON WITH ANY RAIN CHANCES
BEING LIMITED TO THE COAST. WITH THE OFFSHORE FLOW...TEMPERATURES
WILL RISE WELL INTO THE 60S IN THE INTERIOR. THE FRONT ASSOCIATED
WITH THE OFFSHORE TROUGH WILL FINALLY MOVE INTO WASHINGTON SUN NIGHT
OR MON OF NEXT WEEK. ALBRECHT

&&

.AVIATION...AS THE FRONT PUSHES ON PAST THE CASCADES...SOME POST
FRONTAL SHOWERS MAY LINGER OVER PORTIONS OF WESTERN WASHINGTON
TODAY. SOUTHWESTERLY FLOW ALOFT WILL REMAIN IN PLACE UNTIL THE UPPER
LEVEL TROUGH STARTS TO MOVE EASTWARD WEDNESDAY. CIGS GENERALLY
RANGING VFR TO MVFR...ALTHOUGH ISOLATED IFR CONDITIONS MAY EXIST IN
SOME LOCATIONS FOR THE REMAINDER OF THE MORNING.  MOIST SW FLOW WILL
CONTINUE THIS AFTERNOON FOR CONTINUED THREAT FOR SHOWERS. THE AIR
MASS WILL REMAIN UNSTABLE TONIGHT WITH A CHANCE OF THUNDERSTORMS
COAST AND SOUTH PART. 33/SMR

KSEA...WITH FRONT TO THE EAST...VFR CONDITIONS EXPECTED THIS
MORNING. CHANCE FOR SHOWERS AND LOWERING CIGS INTO MVFR THIS
AFTERNOON AND EVENING WITH CONTINUED MOIST SW FLOW. SURFACE WINDS
WILL REMAIN SOUTHERLY. 33/SMR

&&

.MARINE...WINDS WILL BE GENERALLY LIGHT AS HIGH PRES SHIFTS INLAND
THIS AFTERNOON AND EVENING. WEST SWELLS 10 TO 11 FT
TODAY...WARRANTING A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR THE
COASTAL WATERS. WILL REEVALUATE WHEN 12Z DATA COMES IN...BUT AT
FIRST GLANCE...LOOKS LIKE THIS MAY NEED TO BE EXTENDED INTO TOMORROW
FOR AFTERNOON FORECAST PACKAGE.

A SURFACE TROUGH...ASSOCIATED WITH A 984 MB LOW NEAR HAIDA
GWAII...WILL SHIFT INLAND ON WED. MAY SEE SMALL CRAFT ADVISORY WINDS
OVER PUGET SOUND AND HOOD CANAL. A STRONGER PACIFIC FRONTAL SYSTEM
WILL IMPACT THE REGION THU THROUGH FRI. MODELS CONTINUE TO SHOW
GALES OVER THE COASTAL WATERS DURING THIS PERIOD. GALES MAY ALSO
OCCUR AT THE WEST/EAST STRAIT OF JUAN DE FUCA. EXPECT COMBINED SEAS
OF 12 TO 20 FT. 33/SMR

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS COASTAL WATERS.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

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