Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

343
FXUS66 KSEW 280934
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
234 AM PDT THU APR 28 2016

.SYNOPSIS...AN UPPER RIDGE WILL MOVE OVER THE REGION TODAY...FOR
PARTLY SUNNY SKIES ACROSS WESTERN WASHINGTON. SPOTTY LIGHT SHOWERS
COULD DEVELOP OVER THE MOUNTAINS LATE TODAY. A FRONT AND ITS
UPPER TROUGH WILL BRING SHOWERS LATE TONIGHT AND FRIDAY. A STRONG
UPPER RIDGE WILL BRING DRY WARMER WEATHER SATURDAY THROUGH MONDAY.
A CHANCE OF PRECIPITATION WILL RETURN TUESDAY THROUGH WEDNESDAY.

&&

.SHORT TERM...THERE IS A WEAK UPPER TROUGH OVER EASTERN
WASHINGTON EARLY THIS MORNING...WHILE AN UPPER RIDGE IS MOVING
INTO THE OFFSHORE WATERS. THE LIGHT SHOWERS THAT LINGERED OVER THE
NORTH CASCADES LATE WEDNESDAY EVENING ENDED...AND THERE HAS BEEN
LITTLE IF ANY PRECIPITATION ACROSS WESTERN WASHINGTON OVERNIGHT.
SKIES REMAIN GENERALLY CLOUDY THOUGH...WITH 2 AM TEMPERATURES IN
THE 40S TO LOWER 50S.

THE UPPER RIDGE WILL PROGRESS INTO WESTERN WASHINGTON THIS
AFTERNOON. SPOTTY LIGHT SHOWERS WILL PROBABLY DEVELOP OVER THE
OLYMPICS AND CASCADES THIS AFTERNOON...BUT OTHERWISE TODAY SHOULD
BE DRY ACROSS THE FORECAST AREA. A CLEAR TREND OVER THE LAST
COUPLE MODEL RUNS THOUGH SHOWS MORE MOISTURE REMAINING OVER THE
AREA TODAY -- ESPECIALLY BELOW ABOUT 10000 FT -- AND MORE CLOUD
COVER. PARTLY SUNNY LOOKS LIKE A BETTER FORECAST THAN MOSTLY
SUNNY. IT WILL BE A LITTLE WARMER THAN WEDNESDAY WITH HIGHS IN THE
UPPER 50S TO MID 60S.

THE RIDGE WILL MOVE EAST OF THE CASCADES TONIGHT...AND A COLD
FRONT AND ITS UPPER TROUGH WILL APPROACH THE COAST TONIGHT FROM
THE OFFSHORE WATERS. THIS SYSTEM WILL DIG EAST-SOUTHEAST INTO THE
PACIFIC NORTHWEST ON FRIDAY...AND IT SHOULD PRODUCE FAIRLY
WIDESPREAD SHOWERS ACROSS THE FORECAST AREA. IN ADDITION MOIST
ONSHORE FLOW WILL DEVELOP FRIDAY AFTERNOON...AND A RATHER SHORT-
LIVED PUGET SOUND CONVERGENCE ZONE IS LIKELY. HIGHS WILL BE BACK
INTO THE MID 50S TO LOWER 60S ACROSS THE WESTERN WASHINGTON
LOWLANDS. THE SNOW LEVEL WILL BE AROUND 4500 FT...AND 1 TO 3 INCHES
OF SNOW IS LIKELY IN THE MOUNTAINS ABOVE THAT LEVEL.

AN OFFSHORE UPPER RIDGE WILL START BUILDING FRIDAY NIGHT AND MOVE
TO AROUND 130W ON SATURDAY. THE RIDGE WILL BEGIN A SHORT STRETCH
OF DRY WEATHER AND A WARMING TREND. MCDONNAL

.LONG TERM...THE UPPER RIDGE WILL MOVE TO AROUND THE COAST SUNDAY
AND THEN INLAND MONDAY. THERE WILL BE SUNSHINE BOTH DAYS. HIGHS
SHOULD BE IN THE MID TO UPPER 70S OVER MUCH OF THE AREA ON SUNDAY
AND INTO THE LOWER 80S ON MONDAY. IT LOOKS LIKE THE RIDGE WILL
MOVE EAST AND BREAK DOWN AFTER THAT...BUT MODELS DIFFER ON HOW
THAT WILL HAPPEN. MOIST SOUTHERLY FLOW ALOFT WEST OF THE RIDGE
COULD BRING SOME SHOWERS AND CONVECTION INTO THE AREA MONDAY NIGHT
OR TUESDAY...OR POSSIBLY A MORE ORGANIZED SYSTEM WILL ARRIVE FROM
THE WEST. AT ANY RATE...THERE IS A CHANCE OF PRECIPITATION AGAIN
MONDAY NIGHT THROUGH WEDNESDAY. MCDONNAL

&&

.AVIATION...SOME LINGERING CLOUDS REMAIN OVER PORTIONS OF WESTERN
WASHINGTON THIS EARLY MORNING...BUT CIGS AT ALL TAF SITES REMAIN AT
OR ABOVE 5K FT...SO CONDITIONS REMAIN VFR AND WILL REMAIN AS SUCH
THROUGH THE MORNING AND INTO THE AFTERNOON. THE EXCEPTION
POTENTIALLY BEING FOG PRONE AREAS...SUCH AS OLM...BUT CURRENT OB
SHOWS CIGS THERE CURRENTLY AT OR AROUND 10K FT. THIS MIGHT BE ENOUGH
TO KEEP FOG FROM DEVELOPING. STILL...A CHANCE IS A CHANCE...SO TEMPO
GROUP FOR A DIP IN VIS THERE WILL REMAIN. CIGS EXPECTED TO START TO
LOWER TONIGHT IN ADVANCE OF APPROACHING FRONT THAT WILL MOVE THROUGH
THE AREA FRIDAY...ALTHOUGH ARE EXPECTED TO REMAIN VFR. SMR

KSEA...CIGS GENERALLY REMAINING VFR FOR THE 24 HOUR PERIOD. LIGHT
VARIABLE WINDS THIS MORNING GIVING WAY TO WEST TO SOUTHWEST WINDS
THIS AFTERNOON WITH SPEEDS 5 TO 10 KTS. SMR

&&

.MARINE...ONSHORE FLOW WILL CONTINUE WITH HIGH PRESSURE OVER
THE COASTAL WATERS AND LOWER PRES INLAND. WINDS IN THE STRAIT
EXPECTED TO REACH SMALL CRAFT ADVISORY SPEEDS AGAIN TODAY...THUS
HAVE HOISTED ANOTHER ROUND OF ADVISORIES FOR TODAY. STRONGER WINDS
ARE EXPECTED FOR COASTAL WATERS BEHIND FRONT PROGGED TO MOVE THROUGH
THE WATERS OVERNIGHT THURSDAY AND INTO FRIDAY...WHICH MAY REQUIRE
ITS OWN SET OF ADVISORIES...BUT AT THIS TIME HAVE LEFT FOR NEXT
SHIFT TO TACKLE. THE PASSAGE OF THIS FRONT LOOKS TO BRING A BREEZY
PERIOD TO MOST WESTERN WASHINGTON WATERS FOR MUCH OF FRIDAY BEFORE
SLOWLY DIMINISHING THROUGH THE DAY ON SATURDAY. SMR

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 8 AM PDT FRIDAY
     FOR EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS
     EVENING FOR WEST ENTRANCE U.S. WATERS STRAIT OF JUAN DE
     FUCA.

     SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 AM PDT FRIDAY
     FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.