Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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673
FXUS66 KSEW 291613
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
913 AM PDT FRI APR 29 2016

.SYNOPSIS...A FRONT AND ITS UPPER TROUGH WILL MOVE THROUGH WESTERN
WASHINGTON TODAY FOR OCCASIONAL SHOWERS OVER MOST OF THE AREA. A
STRONG UPPER RIDGE WILL BRING DRY WARMER WEATHER SATURDAY THROUGH
MONDAY. A CHANCE OF SHOWERS WILL RETURN TUESDAY THROUGH THURSDAY
OF NEXT WEEK...WITH MOIST SOUTHERLY FLOW ALOFT AND LOW LEVEL
ONSHORE FLOW.

&&

.SHORT TERM...AN UPPER TROUGH AND A WEAK FRONT WILL BRING SHOWERS
TODAY. THIS WEATHER SYSTEM WILL RAPIDLY EXIT THE AREA TONIGHT
WITH SHOWERS ENDING IN THE EVENING. HIGHS TODAY WILL BE MAINLY
IN THE MID TO UPPER 50S WHICH IS A FEW DEGREES BELOW NORMAL.

HIGH PRESSURE ALOFT WILL BUILD OVER THE PACIFIC NORTHWEST
SATURDAY WITH NORTHERLY LOW LEVEL FLOW DEVELOPING. SOME CLOUDS
WILL LIKELY LINGER IN THE MORNING...THEN SKIES SHOULD BECOME
MOSTLY SUNNY. HIGHS WILL WARM INTO THE 60S.

THE UPPER RIDGE WILL STRENGTHEN OVER THE AREA ON SUNDAY WITH
INCREASING LOW LEVEL OFFSHORE FLOW. THIS WILL BRING ANOTHER SUNNY
DAY WITH HIGHS WARMING WELL INTO THE 70S OR EVEN LOWER 80S IN THE
USUAL WARMER SPOTS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...THE UPPER RIDGE WILL MOVE
FURTHER EAST ON MONDAY...AND THE AIR MASS WILL WARM A BIT MORE AS
SOUTHERLY FLOW ALOFT DEVELOPS. IT IS CONCEIVABLE THAT SOME MID
LEVEL MOISTURE WILL ACCOMPANY WEAK INSTABILITY OVER THE MOUNTAINS
TO PRODUCE ISOLATED SHOWERS BY LATE MONDAY. THE MODELS HAVE NOT
BEEN CONSISTENT WITH THAT IDEA THOUGH...AND IN COORDINATION WITH
SURROUNDING OFFICES WE WILL STAY WITH A DRY FORECAST FOR NOW.
THERE IS A BETTER CHANCE OF SHOWERS DEVELOPING TUESDAY ALONG WITH
INCREASING ONSHORE FLOW. MOIST SOUTHERLY FLOW ALOFT...WEAK
INSTABILITY...AND LOW LEVEL ONSHORE FLOW WILL KEEP A CHANCE OF
SHOWERS IN THE FORECAST WEDNESDAY AND THURSDAY AS WELL. MCDONNAL

&&

.AVIATION...UPPER LEVEL TROUGH OVER WESTERN WASHINGTON THIS
MORNING WILL SHIFT EAST THIS AFTERNOON. LIGHT FLOW ALOFT BECOMING
NORTHWESTERLY. LOW LEVEL ONSHORE FLOW CONTINUING INTO SATURDAY.

CEILINGS MOSTLY IN THE 1500-2500 FOOT RANGE INTO THE AFTERNOON
HOURS. SOME IMPROVEMENT MID TO LATE AFTERNOON WITH THE CEILINGS
LIFTING TO 3000-4000 FEET. CONVERGENCE OVER NORTH KING AND SNOHOMISH
COUNTY WILL KEEP MVFR CEILINGS BETWEEN KBFI AND KPAE INTO THE
EVENING HOURS.

KSEA...CEILINGS AROUND 1500 FEET INTO THE AFTERNOON HOURS. SOME
IMPROVEMENT LATE AFTERNOON UP TO AROUND 3000 FEET. LIGHT SOUTH
WINDS BECOMING NORTHERLY LATE THIS AFTERNOON INTO THE EVENING HOURS.
FELTON

&&

.MARINE...LOW LEVEL ONSHORE FLOW PATTERN CONTINUING INTO SATURDAY
WITH SMALL CRAFT ADVISORIES OVER THE COASTAL WATERS...IN THE STRAIT
OF JUAN DE FUCA AND THE NORTHERN INLAND WATERS. ONSHORE FLOW TURNS
NORTHWESTERLY ON SATURDAY WITH THE LOW LEVEL FLOW TURNING OFFSHORE
ON SUNDAY. A RETURN TO LOW LEVEL ONSHORE FLOW WILL OCCUR LATER MONDAY
INTO TUESDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 PM PDT SATURDAY FOR COASTAL WATERS
     FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
     WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO 60 NM-
     COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER 10
     TO 60 NM.

     SMALL CRAFT ADVISORY UNTIL 5 AM PDT SATURDAY FOR COASTAL WATERS
     FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-COASTAL WATERS
     FROM JAMES ISLAND TO POINT GRENVILLE OUT 10 NM-COASTAL
     WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER OUT 10 NM-
     WEST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY UNTIL 5 AM PDT SATURDAY FOR CENTRAL U.S.
     WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
     STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO NOON PDT SATURDAY
     FOR NORTHERN INLAND WATERS INCLUDING THE SAN JUAN ISLANDS.

&&

$$

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