Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 060917
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
217 AM PDT FRI MAY 6 2016

.SYNOPSIS...HIGH PRESSURE ALOFT WILL BUILD OVER THE REGION TODAY
AND SATURDAY PROVIDING INCREASED SUNSHINE AND A RETURN TO ABOVE
NORMAL TEMPERATURES. A TROUGH WILL INDUCE MUCH COOLER ONSHORE FLOW
SATURDAY NIGHT THROUGH MONDAY WITH SOME DRIZZLE OR SHOWERS POSSIBLE.
DRY AND WARMER WEATHER RETURNS TUESDAY THROUGH THURSDAY.

&&

.SHORT TERM...RADAR IMAGERY PRETTY QUIET THIS EARLY MORNING AS ANY
ISOLATED SHOWER ACTIVITY OVER THE CASCADE CREST EARLIER IN THE NIGHT
HAS SINCE QUIETED. GETTING SOME ECHOES OUT OVER THE COASTAL
WATERS...BUT WITH IR SATELLITE IMAGERY SHOWING CLEAR SKIES...GOING
TO DISMISS THOSE AS FALSE RETURNS.

UPPER LEVEL RIDGING WILL CONTINUE TO BUILD OVER THE AREA
TODAY...PRODUCING A THERMAL PRESSURE TROUGH BY MID TO LATE THIS
MORNING AND RESULTING IN A BRIEF WINDOW OF OFFSHORE FLOW. STILL...IT
IS AN INSTANCE OF A LITTLE DAB WILL DO YOU AS HIGH TEMPERATURES
TODAY WILL CLIMB INTO THE LOWER TO MID 70S FOR THE MAJORITY OF
LOWLAND LOCATIONS. ONSHORE FLOW LOOKS TO GENTLY CREEP BACK IN FOR
SATURDAY...COOLING OFF THE COAST BACK DOWN INTO THE 60S...BUT MAKES
LITTLE HEADWAY INLAND...ALLOWING FOR TEMPERATURES TO PEAK ON
SATURDAY IN THE HIGH 70S...WITH ISOLATED LOCATIONS GETTING UP TO THE
LOW 80S.

THE RIDGE FINALLY STARTS TO BREAK DOWN SATURDAY NIGHT AS AN UPPER
LEVEL TROUGH DROPS DOWN FROM BRITISH COLUMBIA. PROBABLY START TO SEE
THE EARLIEST CHANCES FOR PRECIP ASSOCIATED WITH THIS FEATURE LATE
SATURDAY NIGHT WITH POPS PERSISTING INTO SUNDAY NIGHT. THE TROUGH
AND ASSOCIATED CLOSED UPPER LEVEL LOW IS TRACKING FURTHER EAST THAN
PREVIOUS MODEL SOLUTIONS. IF THIS SOLUTION REMAINS CONSISTENT...THE
LOW END CHANCE POPS CURRENTLY IN THE FORECAST MAY HAVE TO BE SHAVED
A BIT MORE...POSSIBLY DOWN TO SILENT POPS LESS THAN 10 PCT...BUT
AGAIN...THAT WILL DEPEND ON FUTURE RUNS.

REGARDLESS OF THE CHANCES FOR PRECIP...THIS LOW WILL USHER IN MUCH
COOLER MARINE AIR ALLOWING FOR TEMPS SUNDAY TO BE FAR MORE
SEASONABLE THAN WHAT WESTERN WASHINGTON IS EXPERIENCING.
UNFORTUNATELY...THOSE COOLER TEMPS ARE SHORT LIVED AS A NEW WARMING
TREND IS ALREADY IN THE CARDS FOR MONDAY.

MADE MINOR TWEAKS TO TAKE INTO ACCOUNT THE MORE EASTWARD TRACK OF
NEXT SYSTEM...LOWERING POPS A TOUCH OVER THE AREA...BUT
OTHERWISE...NO MAJOR CHANGES TO INHERITED FORECAST.  SMR

.LONG TERM...STOP ME IF THIS SOUNDS FAMILIAR...UPPER LEVEL RIDGING
OVER THE PACIFIC WILL START TO BUILD INTO THE AREA FOR THE FIRST
HALF OF NEXT WEEK...LEADING TO TEMPERATURES ABOVE SEASONAL NORMALS.
TUESDAY SEES A DRAMATIC JUMP IN TEMPS BACK INTO THE MID 70S IN
LOWLAND LOCATIONS WITH HIGHS WEDNESDAY AND THURSDAY PROGGED FOR
LOWER 80S IN MANY LOCATIONS. SOME SLIGHT COOLING IS POSSIBLE FOR
LATE NEXT WEEK AS AN UPPER LEVEL LOW OVER ALBERTA PUSHES BACK
AGAINST THE RIDGE AND EXERTING A WEAK INFLUENCE OVER THE AREA. NOT
ENOUGH FOR ANY PRECIP...BUT SHAVING OFF A FEW DEGREES FROM FORECAST
HIGH TEMPS AT THAT POINT WOULD CERTAINLY BE WELCOME.  SMR

&&

.AVIATION...FLOW ALOFT OVER WESTERN WASHINGTON HAS SWITCHED FROM
SOUTHERLY TO NORTHEAST OVERNIGHT...AS THE UPPER LEVEL TROUGH
MOVING SLOWLY THROUGH THE AREA HAS SHIFTED EAST OF THE CASCADES
EARLY THIS MORNING. NORTHEAST FLOW ALOFT WILL CONTINUE THROUGH
TONIGHT AHEAD OF AN OFFSHORE UPPER RIDGE.

THE AIR MASS WILL BE GENERALLY DRY WITH NO SIGNIFICANT CLOUD COVER
BELOW 12000 FT...EXCEPT FOR AREAS OF LOW LEVEL MARINE STRATUS OR
FOG ALONG THE COAST THIS MORNING.

KSEA...NORTH WIND 6-12 KT RISING TO 8-16 KT THIS AFTERNOON...
EASING TO 6-12 KT AGAIN AFTER SUNSET. NO SIGNIFICANT CLOUD COVER
BELOW 12000 FT. MCDONNAL

&&

.MARINE...NORTHWEST ONSHORE FLOW WILL PERSIST TODAY AND
TONIGHT...WITH HIGH PRESSURE WELL OFFSHORE AND LOWER PRESSURE EAST
OF THE CASCADES. NORTHWEST SMALL CRAFT ADVISORY WINDS WILL
CONTINUE OVER THE COASTAL WATERS. SMALL CRAFT ADVISORY NORTHERLIES
SHOULD DEVELOP IN THE PUGET SOUND THIS AFTERNOON AND CONTINUE
THROUGH SUNSET...WITH SMALL CRAFT ADVISORY WESTERLIES IN THE
CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA THIS EVENING.

ONSHORE FLOW WILL STRENGTHEN SATURDAY AND SATURDAY NIGHT AS A
STRONG MARINE PUSH DEVELOPS. WESTERLY GALES ARE LIKELY IN THE
CENTRAL STRAIT OF JUAN DE FUCA AND EAST ENTRANCE STRAIT LATE
SATURDAY THROUGH SATURDAY NIGHT. A GALE WATCH WILL BE ISSUED WITH
THE EARLY MORNING FORECAST PACKAGE...WITH A FORECAST OF 30 TO 40
KT WINDS. SMALL CRAFT ADVISORY WINDS ARE LIKELY ALL OTHER MARINE
ZONES EXCEPT PUGET SOUND AND HOOD CANAL.

ONSHORE FLOW SHOULD DIMINISH SLIGHTLY ON SUNDAY...THEN EASE MORE
SIGNIFICANTLY MONDAY AND TUESDAY. MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 6 PM PDT SATURDAY 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.

     GALE WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY NIGHT
     FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
     ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT PDT
     TONIGHT FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
     ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY FROM NOON TODAY TO 9 PM PDT THIS EVENING
     FOR PUGET SOUND AND HOOD CANAL.

&&

$$

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