Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 302200
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PDT SAT APR 30 2016

.SYNOPSIS...HIGH PRESSURE ALOFT WILL BRING DRY AND WARMER WEATHER
THROUGH MONDAY. SOUTHERLY FLOW ALOFT AND LOW LEVEL ONSHORE FLOW
WILL RETURN TUESDAY AND PERSIST FOR MOST OF THE REST OF THE WEEK
FOR A CHANCE OF SHOWERS AND COOLER TEMPERATURES. AN UPPER RIDGE
WILL BRING DRIER AND WARMER WEATHER AGAIN LATE IN THE WEEK.

&&

.SHORT TERM...HIGH PRESSURE ALOFT WILL SHIFT INLAND SUNDAY WITH
LOW LEVEL OFFSHORE FLOW DEVELOPING FOR WESTERN WASHINGTON. HIGHS
WILL RISE INTO THE 70S OR EVEN LOWER 80S IN A FEW SPOTS.

THE HIGH PRESSURE ALOFT WILL SHIFT A LITTLE FURTHER INLAND MONDAY
WITH INCREASING SOUTHERLY FLOW ALOFT. LOW LEVEL OFFSHORE FLOW
WILL EASE BUT A WEAK SURFACE TROUGH WILL REMAIN JUST OFFSHORE.
THIS SHOULD BE THE WARMEST DAY FOR THE INTERIOR...A FEW DEGREES
WARMER THAN SUNDAY. THE COAST WILL REMAIN ABOVE NORMAL BUT
PROBABLY SEE A FEW DEGREES OF COOLING AS SOUTHERLY WINDS DEVELOP
IN THE AFTERNOON.

ONSHORE FLOW WILL INCREASE ALL AREAS TUESDAY WITH AN UPPER TROUGH
MOVING TO NEAR 130W. THE WILL BRING A CHANCE OF SHOWERS TO ALL
AREA AND HIGHS WILL COOL MOSTLY BACK INTO THE 60S. THE AIR WILL BE
UNSTABLE ENOUGH FOR A CHANCE OF THUNDERSTORMS OVER THE CASCADES IN
THE AFTERNOON AND EVENING. SCHNEIDER

.LONG TERM...AN UPPER TROUGH NEAR 130W WILL SLOWLY SHIFT EAST AND
SPLIT...TURNING INTO A CLOSED UPPER LOW ON THURSDAY OVER
CALIFORNIA. MOIST AND SLIGHTLY UNSTABLE SOUTHERLY FLOW ALOFT WILL
CONTINUE FOR WESTERN WASHINGTON...KEEPING A CHANCE OF SHOWERS IN
THE FORECAST. HIGHS WILL BE MOSTLY IN THE 60S.

AN UPPER RIDGE WILL MOVE OVER THE AREA ON FRIDAY AS THE UPPER LOW
TO THE SOUTH MOVES FARTHER SOUTH AND EAST. THIS WILL BRING DRIER
AND SLIGHTLY WARMER WEATHER TO WESTERN WASHINGTON. THE RIDGE
SHOULD BE IN CONTROL BY SATURDAY FOR A MOSTLY SUNNY DAY WITH HIGHS
INTO THE 70S AGAIN FOR SOME LOCATIONS. SCHNEIDER

&&

.AVIATION...UPPER LEVEL RIDGE OFFSHORE EXTENDING INTO SOUTHERN
BRITISH COLUMBIA WITH NORTHEASTERLY FLOW ALOFT. LOW LEVEL
NORTHWESTERLY ONSHORE FLOW TURNING OFFSHORE ON SUNDAY.

SATELLITE IMAGERY SHOWS ISOLATED SC OVER WESTERN WASHINGTON THIS
AFTERNOON. THE SC WILL DISSIPATE BY SUNSET LEAVING JUST SOME HIGH
CLOUDS AT TIMES THROUGH SUNDAY.

KSEA...SOME HIGH CLOUDS AT TIMES. NORTHERLY WIND 8 TO 14 KNOTS
BECOMING NORTHEAST 4 TO 8 KNOTS AFTER 06Z. FELTON

&&

.MARINE...HIGH PRESSURE OFFSHORE EXTENDING INTO SOUTHERN
BRITISH COLUMBIA. SMALL CRAFT ADVISORY NORTHWESTERLIES WILL COME TO
AN END OVER THE COASTAL WATERS OVERNIGHT. LOW LEVEL FLOW TURNING
OFFSHORE ON SUNDAY WITH THERMALLY INDUCED TROUGH ALONG THE COAST. A
RETURN TO LOW LEVEL ONSHORE FLOW WILL OCCUR LATER MONDAY INTO
TUESDAY WITH VARYING DEGREES OF ONSHORE FLOW THROUGH THE END OF THE
WEEK. FELTON

&&

.CLIMATE...APRIL 2016 WILL BE THE WARMEST APRIL ON RECORD IN
SEATTLE. WHAT DOES A WARM APRIL MEAN FOR MAY TEMPERATURES? LOOKING
AT THE PREVIOUS TOP 10 WARMEST APRILS AT SEA-TAC AIRPORT...THE
FOLLOWING MAY WAS WARMER THAN NORMAL 7 TIMES AND COOLER THAN
NORMAL 3 TIMES. THREE OF THE FOLLOWING MAYS ARE IN THE TOP 10
WARMEST MAYS FOR SEA-TAC. RECORDS STARTED AT SEA-TAC AIRPORT IN
1945. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 2 AM PDT SUNDAY FOR COASTAL WATERS
     FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
     WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-COASTAL
     WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO 60 NM-
     COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE OUT 10
     NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER
     10 TO 60 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
     SHOALWATER OUT 10 NM.

&&

$$

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