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000
FXUS66 KSEW 191542
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 AM PDT WED JUN 19 2013

.SYNOPSIS...AN UPPER LEVEL LOW IS OVER THE PACIFIC NORTHWEST.
SCATTERED SHOWERS WILL INCREASE THROUGH THURSDAY...ESPECIALLY NORTH
OF SEATTLE AND IN THE CASCADES. WEAK HIGH PRESSURE WILL BUILD INTO
THE AREA FRIDAY NIGHT AND SATURDAY. A SERIES OF FRONTS WILL BRING
WET WEATHER AGAIN EARLY NEXT WEEK.

&&

.SHORT TERM...THE FLOW ALOFT HAS BACKED TO MORE EASTERLY AS THE
UPPER LOW CENTER SHIFTS OVER OREGON TODAY. SOME SHOWERS HAVE PUSHED
WWD ACROSS THE CASCADES...MAINLY NORTH OF SEATTLE. AT 9AM THIS
MORNING SKIES ACROSS WESTERN WA RANGE FROM SUNNY ON THE COAST TO
CLOUDY INLAND...BUT SOME CU WILL LIKELY LIFT UP AND FILL IN THE
COASTAL AREAS WITH A CHANCE OF SHOWERS THIS AFTERNOON...AND THE
CLOUDY AREAS INLAND WILL PROBABLY SEE SOME SUNBREAKS THIS AFTERNOON.
THE BEST CHANCE OF SHOWERS WILL PROBABLY REMAIN NORTH AND EAST OF
SEATTLE IN THE MORE SOUTHEAST OR EASTERLY FLOW NORTH OF THE LOW
CENTER...AND THERE IS A GOOD CHANCE THAT THE SHOWERS WILL INCREASE
BY THURSDAY. THERE WILL PROBABLY BE A GOOD SOAKING RAIN IN THE NORTH
CASCADES. THE LOW WILL SHIFT INLAND FRIDAY AND WEAK HIGH PRESSURE
WILL BUILD IN TO THE AREA.

&&

.LONG TERM...SATURDAY LOOKS AND WILL LIKELY BE THE WARMEST DAY OF
THE WEEK WITH HIGHS IN THE 70S MANY AREAS AS A SHORT WAVE UPPER
RIDGE MOVES OVERHEAD. A FRONTAL SYSTEM WILL BE APPROACHING FROM THE
WEST SATURDAY NIGHT AND SUNDAY. MODELS ARE HAVING A HARD TIME
AGREEING ON WHEN THIS SYSTEM WILL MAKE LANDFALL AND THERE HAS BEEN A
FAIR AMOUNT OF RUN TO RUN WAFFLING AS WELL. IF THE GFS IS CORRECT...
MOST OF THE AREA WILL REMAIN DRY AND HIGHS WILL BE SIMILAR TO
SATURDAY. IF THE ECMWF IS CORRECT...IT WILL BE A RAINY AND COOLER
DAY WITH HIGHS IN THE 60S. ANOTHER RELATIVELY WET FRONT WILL MOVE
ONSHORE AROUND MONDAY NIGHT. CONFIDENCE IN THE TIMING AND OTHER
SPECIFICS WITH THIS FRONT IS LOW FOR NOW. SCHNEIDER

&&

.AVIATION...UPPER LEVEL LOW OFF THE SOUTH WASHINGTON COAST IS
FORECAST TO MOVE SE INTO NW OREGON BY THIS AFTERNOON AND ACROSS
NORTHERN OREGON TONIGHT INTO THURSDAY. FLOW ALOFT BECOMING MORE
EASTERLY ACROSS WASHINGTON AS THE LOW MOVES INLAND. AIR MASS
UNSTABLE AND BECOMING MORE MOIST INTO THURSDAY. LOW LEVEL ONSHORE
FLOW TO INCREASE THROUGH THURSDAY.

DOPPLER WEATHER RADAR SHOWS INCREASING SHOWERS MOVING WEST INTO THE
CENTRAL AND NORTHERN PUGET SOUND AREA THIS MORNING. CEILINGS IN THIS
REGION HAVE FALLEN INTO THE MVFR CATEGORY. CEILINGS ELSEWHERE REMAIN
VFR. THERE MAY BE SOME IMPROVEMENT IN CEILINGS IN THE MVFR AREAS AS
THE DAY WEARS ON...BUT LIKELY SEE CEILINGS LOWER ELSEWHERE AS MOVE
CLOUD COVER AND SHOWERS MOVE WEST AROUND THE UPPER LOW.

KSEA...MVFR CEILING LIKELY TO LIFT SOME - 2500-3500 FT - BY 19Z OR
SO BUT ALSO SOME SHOWERS TO MOVE IN FROM THE EAST BY 20Z. SOUTHERLY
WINDS 4 TO 8 KNOTS BECOMING SW 6 TO 10 KNOTS THIS AFTERNOON. BUEHNER

&&

.MARINE...A WEAK 1013 MB LOW JUST OFF WILLAPA BAY IS FORECAST TO
SHIFT INLAND TO EASTERN WASHINGTON BY TONIGHT. HIGHER PRES OVER THE
OFFSHORE WATERS WILL BUILD A BIT WITH INCREASING LOW LEVEL ONSHORE
FLOW INTO WESTERN WASHINGTON TONIGHT AND CONTINUING INTO THURSDAY.

A GALE WARNING IS IN PLACE FOR THE CENTRAL AND EASTERN STRAIT OF
JUAN DE FUCA FOR TONIGHT WITH A SMALL CRAFT ADVISORY IN EFFECT UNTIL
THEN. IN ADDITION A SMALL CRAFT ADVISORY REMAINS FOR THE NORTHERN
INLAND WATERS. WINDS EASING LATER THURSDAY AS SURFACE HIGH PRESSURE
BEGINS TO BUILD INTO THE AREA AND PRESSURES RISE OVER BRITISH
COLUMBIA. HIGH PRESSURE OVER THE WATERS ON FRIDAY. A FRONT WILL
APPROACH THE COASTAL WATERS ON SATURDAY AND MOVE INLAND ON SUNDAY.
BUEHNER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...GALE WARNING CENTRAL AND EASTERN STRAIT.
     SMALL CRAFT ADVISORY NORTHERN INLAND WATERS.

&&

$$

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