Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 261533
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT TUE MAY 26 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN THIS WEEK WITH WARMER
AND SUNNIER WEATHER AS THE WEEK PROGRESSES. A WEAK UPPER LOW COULD
BRING SOME SHOWERS AND COOLING EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SHIFT INLAND
OVER THE NEXT FEW DAYS WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON. THERE IS A THREAT OF AFTERNOON AND EVENING
SHOWERS OVER THE CASCADES THROUGH THURSDAY WHERE THE AIR IS MOST
UNSTABLE AND WITH POSSIBLE WRAP AROUND MOISTURE FROM THE UPPER LOW.

ELSEWHERE...LOW LEVEL ONSHORE FLOW WILL CONTINUE...BUT IT WILL
WEAKEN A LITTLE EACH DAY. SKIES ARE CURRENTLY FAIRLY CLOUDY ALTHOUGH
THERE IS A GOOD HOLE IN THE CLOUDS OVER THE SOUTHWEST INTERIOR.
LOOKING OUT THE WINDOW...THERE IS ALREADY SOME BLUE POKING THROUGH
THE CLOUDS. THE NEWEST GFS CROSS SECTION FORECAST SUGGESTS CLOUDS
WILL THIN AND BREAK UP THIS AFTERNOON. THE FORECAST HAS ALREADY BEEN
UPDATED TO REFLECT A LITTLE MORE SUNSHINE TODAY.

IT LOOK LIKE A GOOD BET THAT WEDNESDAY AND THURSDAY WILL SEE
SUNSHINE AFTER SOME MORNING LOW CLOUDS AS LOW LEVEL ONSHORE FLOW
WEAKENS AND THE LOW LEVELS DRY. HIGHS SHOULD WARM INTO THE 70S BOTH
DAYS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...EXTENDED MODELS IN GOOD AGREEMENT
ON FRIDAY WITH AN UPPER LEVEL LOW MOVING SOUTH DOWN THE BRITISH
COLUMBIA COAST BUT STILL FAR ENOUGH NORTH TO NOT BRING ANY WEATHER
TO WESTERN WASHINGTON. LIGHT ONSHORE FLOW CONTINUING AT THE LOWER
LEVELS WITH THE TEMPERATURES ALOFT CONTINUING TO WARM SLIGHTLY.
FRIDAY LOOKS TO BE THE WARMEST DAY IN THE FORECAST PERIOD WITH HIGHS
IN THE 70S TO LOWER 80S. MODELS CONTINUE TO BE IN GOOD AGREEMENT ON
SATURDAY WITH THE ECMWF NOW MORE IN LINE WITH THE GFS SOLUTION OF
MOVING THE LOW OFF TO THE EAST OVER CENTRAL BRITISH COLUMBIA.
ANOTHER SUNNY DAY FORECAST BUT WITH A LITTLE INCREASE IN THE LOW
LEVEL ONSHORE FLOW MAX TEMPERATURES A COUPLE OF DEGREES COOLER THAN
FRIDAY. ONSHORE FLOW CONTINUES TO INCREASE ON SUNDAY WITH AN UPPER
LEVEL TROUGH DIGGING OFFSHORE AND THE UPPER LEVEL LOW CONTINUING TO
MOVE EAST. TEMPERATURES ALOFT BEGIN TO COOL AS THE UPPER LEVEL
TROUGH OFFSHORE APPROACHES WITH 500 MB HEIGHTS LOWERING FROM THE MID
TO UPPER 570 DMS DOWN TO NEAR 570 DMS. THIS WILL KEEP THE COOLING
TREND GOING OVER WESTERN WASHINGTON WITH HIGHS IN THE UPPER 60S TO
MID 70S. TROUGH SWINGING INLAND ON MONDAY CONTINUING THE COOLING
TREND AND ADDING A CHANCE OF SHOWERS TO THE FORECAST. FELTON

&&

.AVIATION...AN UPPER LEVEL LOW WILL REMAIN OVER EASTERN WASHINGTON
TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN WASHINGTON. THERE ARE
AREAS OF LOW CLOUDS THAT SHOULD BURN OFF FOR THE AFTERNOON. SOME MID
LEVEL MOISTURE WILL PROBABLY COME DOWN FROM B.C. IN THE NLY FLOW
LATER THIS AFTERNOON AND EVENING. AREAS OF LOW CLOUDS WILL DEVELOP
AGAIN OVERNIGHT.

KSEA...THE LOW CLOUDS SHOULD BURN OFF AND THEN LATER TODAY SOME MID
LEVEL CLOUDS OUGHT TO DRIFT DOWN FROM B.C...THEN LOW CLOUDS AGAIN
LATE TONIGHT.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. SMALL CRAFT ADVISORY STRENGTH WEST WINDS OF
15 TO 25 KT WILL DEVELOP IN THE STRAIT OF JUAN DE FUCA LATE THIS
AFTERNOON OR EVENING.

&&

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

&&

$$

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