Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 252238
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
245 PM PST WED FEB 25 2015

.SYNOPSIS...LIGHT RAIN WILL BECOME MORE WIDESPREAD THIS EVENING AS A
WEAK SYSTEM MOVES INTO THE AREA. A SHOWERY PATTERN WILL PERSIST
THROUGH FRIDAY. OFFSHORE FLOW AND AN UPPER RIDGE WILL GIVE DRY
WEATHER SATURDAY AND SUNDAY. A WETTER AND COOLER PATTERN WILL RETURN
EARLY NEXT WEEK.

&&

.SHORT TERM...A BLOB OF RAIN ASSOCIATED WITH A SHORT WAVE IS
APPARENT ON RADAR OFF THE CENTRAL COAST. THIS RAIN IS FORECAST TO
SPREAD INLAND OVERNIGHT. THE RAIN SHOULD TURN MORE SHOWERY AFTER
MIDNIGHT. SHOWERS ARE LIKELY THURSDAY THEN THEY WILL TAPER THURSDAY
NIGHT...EXCEPT ON THE COAST WHERE AN UPPER LEVEL TROUGH WILL ENHANCE
SHOWERS AND KEEP THEM GOING INTO FRIDAY. THERE IS SOME INSTABILITY
ASSOCIATED WITH THE UPPER TROUGH SO HAVE PUT A SLIGHT CHANCE OF
THUNDERSTORMS INTO THE COAST AND OLYMPICS FRIDAY.

A NORTHERLY AND OFFSHORE SURFACE GRADIENT SETS UP OVER WESTERN
WASHINGTON ON FRIDAY NIGHT CONTINUING INTO SATURDAY. THIS WILL GIVE
BREEZY CONDITIONS TO MANY AREAS...AND WILL CLEAR THINGS OUT FROM
NORTH TO SOUTH ON SATURDAY. HIGHS BOTH THURSDAY AND FRIDAY WILL BE
IN THE LOW 50S...VERY CLOSE TO NORMAL FOR THIS TIME OF YEAR. ON
SATURDAY THE HIGHS WILL BE A FEW DEGREES LOWER AS COLDER AIR SEEPS
IN FROM THE NORTH. A MORE NOTICEABLE CHANGE WILL BE WITH OVERNIGHT
LOWS...WHICH WILL FALL FROM THE LOW 40S TONIGHT TO THE LOW AND MID
30S SATURDAY NIGHT. BURKE

.LONG TERM...SUNDAY WILL BE MOSTLY SUNNY AND TEMPERATURES WILL
REBOUND A BIT. THE GFS AND EURO BOTH HAVE A WEAK SYSTEM MOVING
ALMOST DUE SOUTH ALONG THE COAST SUNDAY NIGHT AND MONDAY. CHANCE
POPS COVER THIS SYSTEM FOR NOW. AFTER IT PASSES NORTHERLY AND
OFFSHORE FLOW WILL AGAIN DEVELOP WITH MONDAY NIGHT AND TUESDAY
LOOKING BREEZY AND COOL. DRY WEATHER CONTINUES THROUGH WEDNESDAY.
HIGH TEMPERATURES ON TUESDAY AND WEDNESDAY WILL BE MOSTLY IN THE 40S
WITH LOWS IN THE 30S. BURKE

&&

.HYDROLOGY...FLOODING IS UNLIKELY THE NEXT 7 DAYS.

&&

.AVIATION...NORTHWEST FLOW ALOFT. LIGHT PRESSURE GRADIENTS AT THE
SURFACE. THE AIR MASS IS STABLE AND MOIST. A WEAK WEATHER SYSTEM
MOVED INTO WESTERN WA THIS AFTERNOON AND WILL SLOWLY DRAG THROUGH
THE AREA TONIGHT. THERE HAVE BEEN AREAS OF LIGHT RAIN OR DRIZZLE AND
THAT SHOULD CONTINUE TONIGHT. CONDITIONS SHOULD IMPROVE BEHIND THE
SYSTEM DURING THE DAY THURSDAY. THE MOUNTAINS WILL REMAIN MOSTLY
OBSCURED THROUGH THURSDAY MORNING.

KSEA...CLOUDY WITH A LITTLE LIGHT RAIN OR DRIZZLE AT TIMES. THE
OLM-BLI GRADIENT SUGGESTS THAT A NLY BREEZE IS LIKELY TONIGHT.

&&

.MARINE...PRESSURE GRADIENTS ARE LIGHT AND THE WEATHER SYSTEM THAT
WILL BE OVER THE AREA THROUGH TONIGHT IS RATHER WEAK. A WEAK LOW
WILL DROP S OVER THE COASTAL WATERS LATE THU NIGHT INTO FRI.
PRESSURE GRADIENTS ARE EXPECTED TO REMAIN LIGHT OVER THE WATERS AS
THE LOW PASSES SOUTHWARD ACROSS THE AREA. THEN HIGH PRESSURE WILL
DEVELOP OVER BRITISH COLUMBIA FRIDAY AND FRIDAY NIGHT. THE
COMBINATION OF THE BUILDING HIGH AND THE SURFACE LOW DEPARTING TO
THE SOUTH OF THE AREA WILL RESULT IN STRONGER NE FLOW OVER THE AREA
FRI NIGHT INTO SAT WITH SMALL CRAFT ADVISORY CONDITIONS EXPECTED
EVERYWHERE EXCEPT IN ADMIRALTY INLET AND PUGET SOUND/HOOD CANAL.
GALE FORCE WINDS ARE POSSIBLE AROUND THE WEST ENTRANCE OF THE STRAIT
OF JUAN DE FUCA EARLY SATURDAY MORNING. PRES GRADIENTS WILL RELAX ON
SUN AS HIGH PRES MOVES OVER THE WATERS.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.

&&

$$

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