High Wind in Washington, March 14, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 AM PDT MON MAR 14 2011

.SYNOPSIS...WESTERN WASHINGTON WILL BE SHOWERY AND BREEZY TODAY WITH
A FEW SUN BREAKS. SNOW WILL CONTINUE IN THE MOUNTAINS. ANOTHER
VIGOROUS FRONTAL SYSTEM WILL MOVE THROUGH THE AREA TONIGHT THROUGH
TUESDAY NIGHT WITH RAIN AND ISOLATED THUNDERSTORMS...MOUNTAIN
SNOW...AND WINDY CONDITIONS. COOL AND OCCASIONALLY SHOWERY BUT
RELATIVELY QUIET WEATHER IS EXPECTED THURSDAY THROUGH THE WEEKEND.

&&

.SHORT TERM...A VIGOROUS POST-FRONTAL VORTICITY LOBE AND BENT BACK
OCCLUSION IS MOVING THROUGH WESTERN WASHINGTON EARLY THIS MORNING.
THIS IS THE FINAL FEATURE ASSOCIATED WITH THE STRONG FRONTAL SYSTEM
THAT MOVED INTO THE AREA SATURDAY NIGHT. IT IS BRINGING WIDESPREAD
SHOWERS...ISOLATED THUNDERSTORMS MAINLY AT THE COAST...AND WINDY
CONDITIONS ESPECIALLY ALONG THE COAST AND IN THE NORTHWEST INTERIOR.

THIS FEATURE WILL BE MOVING NORTHEAST OF THE AREA DURING THE NEXT
FEW HOURS...AND A MINOR UPPER RIDGE WILL MOVE ACROSS WESTERN
WASHINGTON THIS AFTERNOON FROM THE SOUTHWEST. MOST ALL OF WESTERN
WASHINGTON WILL RECEIVE SHOWERS AT SOME TIME TODAY...BUT WE WILL BE
BETWEEN STORMS. SATELLITE IMAGERY ALSO STRONGLY SUGGESTS THAT THERE
WILL BE ENOUGH HOLES IN THE CLOUD COVER TO MENTION SUN BREAKS TODAY.

PRECIPITATION AMOUNTS TODAY WILL BE RELATIVELY LIGHT -- 0.25 TO 1.00
INCH OVER THE MOUNTAINS...WITH THE SNOW LEVEL AROUND 2500 FT. FOR
THE LOWLANDS AMOUNTS WILL BE AROUND 0.10 TO 0.50 AT THE COAST AND UP
TO 0.25 OVER THE INTERIOR LOWLANDS.

THE MARGINAL HIGH WIND WARNING FOR THE COAST IS SET TO EXPIRE AT 5
AM AND THE WIND ADVISORY FOR THE NORTHWEST INTERIOR AT 6 AM. NO
QUESTION WINDS WILL GRADUALLY EASE THIS MORNING. I HAVE NOT SEEN ANY
REPORTS OF HIGH WIND IN THE WARNING AREA -- THOUGH IT HAS BEEN CLOSE
AT A COUPLE SPOTS --- AND I WILL END THAT WARNING WITH THE ISSUANCE
OF THE MORNING PACKAGE. THE WIND ADVISORY WILL REMAIN IN EFFECT FOR
A WHILE LONGER THIS MORNING.

AS WE HAVE BEEN ADVERTISING...ANOTHER VIGOROUS PACIFIC FRONTAL
SYSTEM WILL AFFECT THE AREA TONIGHT THROUGH TUESDAY NIGHT. THIS
SYSTEM IS CURRENTLY DEVELOPING OUT NEAR 45N/140W AS A 140 KT
WESTERLY JET MOVES INTO THE BASE OF THE DEEP UPPER TROUGH DOMINATING
THE GULF OF ALASKA. RAIN WILL SPREAD INTO WESTERN WASHINGTON
TONIGHT...ITS OCCLUDED FRONT WILL SWING THROUGH TUESDAY MORNING...
AND ANOTHER POST-FRONTAL TROUGH OR BENT BACK FEATURE WILL FOLLOW
THAT AROUND TUESDAY EVENING.

ALL IN ALL...ANOTHER RAINY AND WINDY PERIOD QUITE SIMILAR TO THE
PAST DAY AND A HALF. INSTABILITY AND DYNAMICS ASSOCIATED WITH THE
FRONT AND THE POST-FRONTAL FEATURE PRESENT A LIKELIHOOD OF ISOLATED
THUNDERSTORMS.

STORM TOTAL PRECIPITATION FOR TONIGHT THROUGH TUESDAY NIGHT WILL BE
ROUGHLY ANOTHER 1.5 TO 4.0 INCHES OVER THE OLYMPIC MOUNTAINS AND 1.0
TO 2.5 INCHES OVER THE CASCADES...WITH THE SNOW LEVEL 3000 TO 3500
FEET. THE WINTER STORM WARNING FOR HEAVY SNOW WILL REMAIN IN EFFECT
AND BE UPDATED WITH THE MORNING PACKAGE. OVER THE LOWLANDS WE CAN
EXPECT GENERALLY 1.0 TO 2.0 INCHES OF RAIN AT THE COAST AND 0.25 TO
1.25 OVER THE INTERIOR LOWLANDS.

WEDNESDAY WILL BE A COOL SHOWERY DAY IN THE WAKE OF THE STRONG
FRONTAL SYSTEM. SNOW WILL CONTINUE IN THE MOUNTAINS WITH THE SNOW
LEVEL AROUND 2000 FT. THE AIR MASS ALOFT WILL BE COOL ENOUGH TO
POTENTIALLY SUPPORT MORE THUNDERSTORMS. HOWEVER THE DYNAMICS THEN
OVER WESTERN WASHINGTON WILL BE WEAK...AND SUNSHINE ALONE MAY NOT BE
STRONG ENOUGH TO TRIGGER THEIR DEVELOPMENT. SO THEY WILL BE LEFT OUT
OF THE FORECAST FOR NOW.  MCDONNAL

.LONG TERM...THE EXTENDED PERIOD THURSDAY THROUGH SUNDAY WILL BE
RELATIVELY UNEVENTFUL...ESPECIALLY BY THE STANDARDS OF THE PAST WEEK
OR SO. SHOWERS ARE LIKELY ACROSS WESTERN WASHINGTON ON
THURSDAY...BUT PRECIPITATION AMOUNTS WILL BE GENERALLY LIGHT AND
SOME AREAS SHOULD REMAIN DRY. ALL MODELS SHOW ANOTHER FRONTAL SYSTEM
DEVELOPING WELL OFFSHORE THURSDAY...WITH ITS CORE MOVING INLAND
ACROSS OREGON AND NORTHERN CALIFORNIA ON FRIDAY. THEY DIFFER HOWEVER
ON WHETHER THIS SYSTEM WILL BRING PRECIPITATION TO WESTERN
WASHINGTON. MODELS DISAGREE FOR SATURDAY AND SUNDAY AS WELL...SO THE
CURRENT FORECAST OF NEAR CLIMATOLOGY POPS AND SOMEWHAT COOL
TEMPERATURES LOOKS GOOD.  MCDONNAL

&&

.HYDROLOGY...THE SKOKOMISH RIVER REACHED FLOOD STAGE EARLY SUNDAY
EVENING AND CRESTED AROUND 16.8 FT JUST AFTER MIDNIGHT. IT WILL FALL
SLOWLY TO AROUND FLOOD STAGE AGAIN TONIGHT. AS MENTIONED ABOVE THE
NEXT FRONTAL SYSTEM WILL BRING ANOTHER 1.5 TO 4.0 INCHES OVER THE
OLYMPIC MOUNTAINS TONIGHT THROUGH TUESDAY NIGHT. OUR QPF CALLS FOR A
MEAN AREAL PRECIPITATION OF 2.7 INCHES OVER THE SKOKOMISH BASIN
DURING THAT 36-HOUR PERIOD...AND WITH THE SNOW LEVEL 3000 TO 3500 FT
MOST OF IT WILL FALL AS RAIN. THE LATEST NWRFC GUIDANCE FOR THE
SKOKOMISH SHOWS IT REACHING ANOTHER CREST WEDNESDAY SIMILAR TO THE
ONE A COUPLE HOURS AGO. IT SHOULD EVENTUALLY FALL BELOW FLOOD STAGE
LATE THURSDAY.

FLOODING LOOKS UNLIKELY ON ANY RIVER IN THE FORECAST AREA OTHER THAN
THE EXCEPTIONALLY FLOOD-PRONE SKOKOMISH. THE CURRENT PATTERN...WHILE
QUITE WET...IS REALLY NOT SIMILAR TO THE CLASSIC FLOOD PRODUCING
PATTERN FOR WESTERN WASHINGTON. THE ONLY OTHER RIVERS THAT WILL NEED
TO BE WATCHED CLOSELY ARE THE CHEHALIS AND SKOOKUMCHUCK...WHICH
EXPERIENCED MINOR FLOODING LAST FRIDAY ON THEIR MOST FLOOD-PRONE
REACHES.

THE GREEN RIVER IS NOT EXPECTED TO FACE A FLOOD THREAT IN THE NEXT
TEN DAYS.  MCDONNAL

&&

.AVIATION...A BENT BACK OCCLUDED FRONT MOVING ACROSS WESTERN
WASHINGTON EARLY THIS MORNING WILL PULL NE OF THE AREA BY 15Z. UNTIL
THEN EXPECT 3-5SM SHRA BKN025-035. ALONG THE COAST AND IN THE
INTERIOR VALLEYS EXPECT S TO SW WINDS 15-25KT WITH GUSTS TO 35 KT TO
CONTINUE UNTIL THE OCCLUSION MOVES OUT WITH WINDS GRADUALLY
DIMINISHING DURING THE DAY TODAY. THE AIR MASS IS SOMEWHAT UNSTABLE
THIS MORNING AS THE OCCLUSION MOVES THROUGH...EXPECT CONDITIONS TO
GRADUALLY STABILIZE LATER THIS MORNING THROUGH THIS EVENING.

CONDITIONS WILL IMPROVE TO P6SM SCT-BKN035 BKN050 MIDDAY WITH SCT
-SHRA. SHOWERS WILL BRIEFLY COME TO AN END LATE THIS AFTERNOON.

ANOTHER STRONG FRONT WILL APPROACH THE AREA FROM THE WEST TONIGHT.
EXPECT THE PRECIPITATION SHIELD TO REACH THE COAST BY 03Z AND THE
INTERIOR BY 06Z. LOW LEVEL OFFSHORE PRES GRADIENTS IN ADVANCE OF THE
FRONT WILL LIKELY KEEP THE CIGS AROUND 040 WITH THE -RA TONIGHT IN
THE INTERIOR VALLEYS EAST OF PUGET SOUND.

KSEA...S WIND 12-16 KT. GUSTS TO 25 KT CAN BE EXPECTED UNTIL ABOUT
15Z. SHOWERS WILL GRADUALLY DIMINISH AFTER 15Z. FROM MIDDAY ONWARD
EXPECT P6SM VCSH SCT035 BKN050 TO DOMINATE. WINDS 050-100 OF 50 KT
THIS MORNING WILL RELAX TO 35 KT MIDDAY. WINDS ALOFT WILL INCREASE
AGAIN AFTER 06Z AS THE NEXT STRONG FRONT APPROACHES FROM THE WEST.
ALBRECHT

&&

.MARINE...A BENT BACK OCCLUDED FRONT ASSOCIATED WITH A 978 MB LOW
OFF NORTHERN VANCOUVER ISLAND WILL MOVE NE INTO CANADA EARLY THIS
MORNING. GALES WILL END AROUND 15Z AT THE ENTRANCES TO THE
STRAIT...IN THE NORTHERN INLAND WATERS...AND IN ADMIRALTY INLET.
GALE FORCE WINDS WILL LIKELY HANG ON UNTIL EARLY AFTERNOON IN THE
COASTAL WATERS.

ANOTHER STRONG FRONT WILL SWEEP ACROSS THE WATERS LATE TONIGHT INTO
MIDDAY TUE. GALES WILL REDEVELOP ON THE COAST. GALES WILL LIKELY
REDEVELOP TONIGHT THROUGH THE STRAIT AND IN THE NORTHERN INTERIOR
WATERS AS WELL...BUT THE TIMING AND LOCATION OF THE GALES IS STILL
UNCERTAIN ENOUGH THAT THE GALE WATCH WAS CONTINUED THERE. GALES MAY
ALSO DEVELOP OVERNIGHT IN ADMIRALTY INLET.

ONSHORE FLOW WILL GRADUALLY DIMINISH WED THROUGH THU.

A LARGE SWELL TRAIN GENERATED BY THE OFFSHORE SYSTEM IS SWEEPING
ONSHORE TODAY AND WILL CONTINUE THROUGH EARLY THIS EVENING. EXPECT A
W TO SW SWELL OF 20 TO 25 FT TO PRODUCE HAZARDOUS SURF ON THE COAST.
ALBRECHT

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA....FLOOD WARNING FOR THE SKOKOMISH RIVER IN MASON COUNTY.
     .WIND ADVISORY FOR THE NORTHWEST INTERIOR EARLY THIS MORNING.
     .WINTER STORM WARNING FOR THE CASCADES AND OLYMPICS THROUGH
        TUESDAY EVENING.
     .HIGH SURF ADVISORY NORTH AND CENTRAL WASHINGTON COAST THROUGH
        THIS EVENING.

PZ...GALE WARNING COAST THROUGH TUESDAY MORNING.
    .GALE WARNING ENTRANCES STRAIT OF JUAN DE FUCA...NORTHERN
       INLAND WATERS...ADMIRALTY INLET THROUGH 8 AM THIS MORNING.
    .GALE WATCH FOR THE STRAIT...NORTH INLAND WATERS...AND ADMIRALTY
       INLET TONIGHT THROUGH TUE MORNING.
    .SMALL CRAFT ADVISORY PUGET SOUND AND HOOD CANAL...CENTRAL
       STRAIT.
    .SMALL CRAFT ADVISORY GRAYS HARBOR BAR FOR ROUGH BAR CONDITIONS.

FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.