Heavy Snow in Washington, November 11 to 12, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
935 AM PST SUN NOV 11 2012

.SYNOPSIS...A FRONTAL SYSTEM WILL SPREAD RAIN AND MOUNTAIN SNOW
ACROSS WESTERN WASHINGTON TODAY AND TONIGHT...WITH WINDY CONDITIONS
AT THE COAST AND IN THE ADMIRALTY INLET AREA. MOIST ONSHORE FLOW
WILL BRING SHOWERS MONDAY AND TUESDAY. WEAK RIDGING WILL BRING
GENERALLY DRY WEATHER WEDNESDAY. MOIST SOUTHWEST FLOW ON THURSDAY OR
FRIDAY WILL BRING A RETURN TO WET WEATHER FOR THE REMAINDER OF THE
WEEK.

&&

.SHORT TERM...RAIN STARTED SPREADING ONTO THE COAST BEFORE DAYBREAK
AND IS NOW MAKING INROADS INTO THE PUGET SOUND REGION. AS A FRONT
CONTINUES TO MOVE ONSHORE TODAY...RAIN AND MOUNTAIN SNOW WILL
EVENTUALLY AFFECT THE ENTIRE FORECAST AREA. A WINTER WEATHER
ADVISORY IS ALREADY IN EFFECT FOR THE CASCADES...WHERE COOL EASTERLY
FLOW WILL KEEP SNOW LEVELS LOCALLY LOWER NEAR THE PASSES UNTIL
MID-DAY MONDAY. LOOKING LIKE A HIGH-END WINTER WEATHER ADVISORY
EVENT FOR BOTH THE PASSES AND VOLCANOES.

WINDY CONDITIONS TODAY WILL FOCUS ALONG THE COAST AND IN THE
ADMIRALTY INLET AREA...BUT SPEEDS ARE EXPECTED TO REMAIN BELOW WIND
ADVISORY CRITERIA.

BY MONDAY MORNING...THE FRONT WILL HAVE EXITED. WE WILL BE LEFT WITH
AN UPPER TROUGH TRYING TO SAG IN FROM THE NORTHWEST AND WESTERLY
FLOW ALOFT. THIS WILL LEAD TO A SHOWERY PATTERN FOR MONDAY AND
TUESDAY.        HANER

.LONG TERM...FROM PREVIOUS DISCUSSION...THE UPPER TROUGH MENTIONED
JUST ABOVE WILL MOVE THROUGH ON WEDNESDAY. THE PORTION OVER WESTERN
WASHINGTON WILL WEAKEN DRAMATICALLY THOUGH AS AN UPPER LOW CLOSES
OVER THE CALIFORNIA OFFSHORE WATERS. WEDNESDAY SHOULD BE A DRY OR
MOSTLY DRY DAY. THE LOW WILL BEGIN OPENING ON THURSDAY...AND
MOISTURE EJECTING NORTHEAST FROM IT COULD BRING SOME SHOWERS TO
MAINLY THE SOUTHERN PART OF WESTERN WASHINGTON. A LARGE DEEP UPPER
TROUGH WILL BEGIN TO DOMINATE THE LARGER OFFSHORE REGION OF BRITISH
COLUMBIA AND THE PACIFIC NORTHWEST FRIDAY AND SATURDAY. A SLOW
MOVING FRONTAL SYSTEM AHEAD OF THE TROUGH WILL EVENTUALLY SPREAD
RAIN TO OUR FORECAST AREA.   MCDONNAL

&&

.HYDROLOGY...FLOODING IS UNLIKELY DURING THE NEXT WEEK.   HANER

&&

.AVIATION...AN UPPER TROF OFFSHORE WILL CONTINUE MOVING E DURING THE
DAY TODAY. WLY FLOW ALOFT. EXPECT A FRONTAL SYSTEM TO MOVE ACROSS
THE AREA TONIGHT FOR GUSTY SLY WINDS...ESPECIALLY OVER THE COAST AND
ADMIRALTY INLET AREA.

PRECIP WAS OVERSPREADING THE AREA FASTER THAN WHAT WAS ANTICIPATED.
THIS EXPECT WIDESPREAD CIGS IN THE 1-3K FT RANGE BY 2000 UTC. THERE
IS A CHANCE THAT THE PRECIP WILL START OUT AS SNOW OR A RAIN/SNOW
MIX OVER PARTS OF THE FAR N INTERIOR...ROUGHLY FROM KBLI NWD...BUT
IT WILL LIKELY BE BRIEF. THE MOUNTAINS WILL BE OBSCD.

KSEA...CIGS WILL CONTINUE LOWERING AND WILL BE NEAR 4K FT BY 2000
UTC. AT THIS TIME...NOT EXPECTING ANY VISIBILITY RESTRICTIONS DURING
THE DAY TODAY.

&&

.MARINE...
A 1010 MB LOW WILL DEVELOP OVER THE OFFSHORE WASHINGTON WATERS
DURING THE DAY TODAY. THE FRONTAL SYSTEM ASSOCIATED WITH THE LOW
WILL MOVE NE ACROSS THE AREA TONIGHT.

CONFIDENCE WAS NOT HIGH THAT WINDS WILL REACH GALE FORCE OVER THE
NORTHERN INLAND WATERS DUE TO THE TRACK OF THE SURFACE LOW. WINDS
OVER THIS AREA WILL PROBABLY STAY NELY MUCH OF THE DAY...BECOMING SE
LATER TONIGHT BUT PROBABLY BELOW GALE FORCE. OTHERWISE...EXPECT GALE
FORCE WINDS ACROSS THE REMAINING WATERS AHEAD OF AND WITH THE
FRONT...EXCEPT FOR THE CENTRAL STRAIT OF JUAN DE FUCA...ADMIRALTY
INLET...AND PUGET SOUND/HOOD CANAL WHERE SMALL CRAFT ADVISORY SPEEDS
ARE ANTICIPATED. THERE IS A POSSIBILITY THAT WINDS MIGHT REACH GALE
FORCE OF THE ADMIRALTY INLET THIS EVENING.

SOUTHERLY OR ONSHORE FLOW WILL PREVAIL IN THE WAKE OF THE FRONT ON
MON. ANOTHER...BUT MUCH WEAKER...FRONT MAY AFFECT THE AREA ON TUE.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER WEATHER ADVISORY FOR THE CASCADES FROM 1 PM THIS
     AFTERNOON TIL NOON MON.

PZ...GALE WARNINGS ARE IN EFFECT FOR THE COASTAL WATERS AND THE
     ENTRANCES TO THE STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORIES ARE IN EFFECT FOR THE REMAINING
     WATERS.

&&

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