Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 251537
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 AM PDT MON AUG 25 2014

.SYNOPSIS...AN UPPER RIDGE OVER THE REGION WILL BRING SUNNY AND WARM
WEATHER TO WESTERN WASHINGTON TODAY THROUGH WEDNESDAY. THE RIDGE
WILL MOVE EAST AS AN OFFSHORE UPPER TROUGH APPROACHES THE AREA
THURSDAY AND FRIDAY FOR SOMEWHAT COOLER AND CLOUDIER WEATHER. THE
TROUGH WILL MOVE INLAND THIS WEEKEND FOR A CHANCE OF SHOWERS.

&&

.SHORT TERM...AN UPPER RIDGE JUST OFFSHORE WILL PROVIDE FAIR WEATHER
OVER THE REGION TODAY THROUGH WEDNESDAY AS IT MOVES ONSHORE AND THE
UPPER LEVEL FLOW BECOMES ZONAL. SINCE LOW CLOUDS AND FOG DID NOT
MAKE IT FAR INLAND THIS MORNING...TEMPS WILL BE WARM ACROSS THE AREA
TODAY. MODELS SHOW TUESDAY A BIT WARMER...AND REFLECTED THAT IN THE
FORECAST HIGHS FOR TUESDAY. AS THE ONSHORE PUSH CONTINUES TO GET
STRONGER THROUGH THE WEEK...HIGH TEMPS WILL MODERATE. THE MODELS
SHOW WEDNESDAY A BIT COOLER THAN TUESDAY AND THE FORECAST REFLECTS
THIS AS WELL.

THE ONSHORE PUSH OF LOW CLOUDS AND PATCHY FOG WILL STRENTHEN THROUGH
THE WEEK. TONIGHT IT LOOKS LIKE THE PUSH MAY MAKE IT FURTHER
INLAND...AND WEDNESDAY MORNING THERE IS A CHANCE IT MAY COVER MUCH
OF THE PUGET SOUND REGION. AS THE NIGHTS ARE GETTING LONGER...WE
WILL BEGIN TO SEE PATCHY RADIATION FOG FORM IN PRONE LOCATIONS AS
WELL. JSMITH

.LONG TERM...THE MODELS HAVE STAYED CONSISTENT IN THE LONGER RANGE.
THEY SHOW THE ZONAL FLOW CONTINUING THURSDAY...THEN BACKING TO
SOUTHWEST ON FRIDAY AS AN OFFSHORE UPPER TROUGH APPROACHES THE
REGION. ONSHORE FLOW WILL INCREASE...AND MARINE LAYER STRATUS WILL
PROBABLY PUSH FURTHER INLAND WEDNESDAY NIGHT AND THURSDAY NIGHT. THE
TROUGH SHOULD REACH THE AREA SATURDAY AND MOVE INLAND SUNDAY FOR A
CHANCE OF SHOWERS...BUT PRECIPITATION AMOUNTS WILL PROBABLY NOT BE
VERY SIGNIFICANT.   MCDONNAL/JSMITH

&&

.AVIATION...AN UPPER LEVEL RIDGE OFFSHORE AND EXTENDING NE OVER
SOUTHERN B.C. WILL GIVE NORTHERLY FLOW ALOFT OVER W WA TODAY. THE
RIDGE WILL SHIFT SLOWLY E OVER THE REGION TONIGHT AND TUESDAY. THE
SURFACE HIGH OVER THE NE PACIFIC WILL MAINTAIN A WEAK LOW LEVEL
ONSHORE FLOW PATTERN. THE AIR MASS WILL BE DRY AND STABLE WITH AREAS
OF STRATUS AND MORNING FOG ALONG THE COAST...AND AREAS OF MORNING
STRATUS AND FOG PART WAY INLAND. ISOLATED MORNING VALLEY FOG CAN
ALSO BE EXPECTED OVER PARTS OF THE INTERIOR.

WEAK ONSHORE FLOW LAST NIGHT SPREAD VERY LITTLE STRATUS INLAND...AND
MOST OF THE IMMEDIATE COAST IS STRATUS-FREE THIS MORNING. THE
RADIATION FOG ALONG THE LOWER CHEHALIS RIVER AND THE ISOLATED VALLEY
FOG ELSEWHERE WILL DISSIPATE BY 17Z. UNRESTRICTED VFR CONDITIONS ARE
EXPECTED THE REMAINDER OF THE DAY.

KSEA...UNRESTRICTED VFR CONDITIONS TODAY AND TONIGHT. LIGHT AND
VARIABLE SURFACE WINDS WILL BECOME N-NW 3 TO 8 KT AROUND 20Z AND
CONTINUE THROUGH 06Z. KAM

&&

.MARINE...A LARGE SURFACE HIGH CENTERED NEAR 140W ALONG WITH LOWER
PRESSURE EAST OF THE CASCADES WILL MAINTAIN A WEAK ONSHORE FLOW
PATTERN INTO WEDNESDAY. THE ONSHORE FLOW WILL BE TYPICALLY STRONGEST
DURING THE LATE AFTERNOON AND EVENING HOURS AND WEAKEST DURING THE
MORNING. LOW END SMALL CRAFT ADVISORY WINDS CAN BE EXPECTED IN THE
CENTRAL AND EAST STRAIT EVERY EVENING. AREAS OF STRATUS ALONG THE
COAST AND IN THE STRAIT WILL LIKELY PRODUCE SOME AREAS OF MORNING
FOG EACH MORNING...POSSIBLY DENSE IN SPOTS.

THE OFFSHORE SURFACE HIGH WILL WEAKEN AND START TO MOVE EAST FROM
LATE WEDNESDAY ONWARD AS A SERIES OF WEAKENING FRONTS BRUSH BY TO
THE NORTH. KAM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA
TONIGHT.

&&

$$

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