Gale Warning 63, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
945 AM PST TUE NOV 17 2009

.SYNOPSIS...A DEEP SURFACE LOW OVER THE NORTH TIP OF VANCOUVER
ISLAND WILL CONTINUE MOVING NORTHEAST WITH COLDER AIR AND SHOWERS
SPILLING ACROSS THE REGION IN ITS WAKE. ANOTHER FAIRLY STRONG
FRONTAL SYSTEM WILL BRING MORE RAIN AND AREAS OF STRONG WINDS TO
WESTERN WASHINGTON LATE WEDNESDAY INTO THURSDAY MORNING. A SERIES OF
SYSTEMS WILL AFFECT THE AREA LATER THURSDAY INTO THE WEEKEND.

&&

.SHORT TERM...THE FORECAST IS NOT AS ACTIVE TODAY...BUT WE STILL
HAVE A FEW SHORT TERM THREATS TO HANDLE. HEAVY PRECIP HAS ENDED
ACROSS THE AREA BUT RIVERS ARE STILL RUNNING HIGH. FLOOD WATCHES AND
WARNINGS REMAIN IN EFFECT FOR PORTIONS OF WESTERN WASHINGTON. STRONG
WIND HAS ALSO EASED WITH JUST BREEZY TO WINDY CONDITIONS...NO HIGH
WIND OR ADVISORIES IN EFFECT. WILL CONTINUE TO SEE A THREAT FOR
SHOWERS ACROSS THE REGION TODAY AS THE UPPER LEVEL TROUGH OFFSHORE
SHIFTS INLAND. THE AIR MASS IS UNSTABLE WITH AN EXTENSIVE CU FIELD
OFFSHORE DRIFTING INLAND. THERE HAVE BEEN A FEW LIGHTNING STRIKES AS
WELL...MAINLY OVER THE OCEAN. SHOWERS WILL INCREASE TONIGHT AS THE
TROUGH AXIS PASSES THROUGH.

ANOTHER WARM FRONT WILL IMPACT WESTERN WA WED NIGHT INTO THU. WILL
ONCE AGAIN SEE FREEZING LEVELS RISE TO OVER 5000 FT ACROSS THE
OLYMPICS WITH ANOTHER ROUND OF HEAVY RAIN FORECAST...IN ADDITION TO
STRONG WINDS ALONG THE COAST AND NORTH INTERIOR. WILL LOOK MORE
CLOSELY AT THIS FOR THE AFTERNOON PACKAGE. HEAVY RAIN ALSO POSSIBLE
IN THE NORTH CASCADES...BUT FREEZING LEVELS ARE NOT AS HIGH. THIS
BAROCLINIC BAND MAY LINGER OVER THE REGION THROUGH INTO FRI. 33

.LONG TERM...PREVIOUS DISCUSSION...THE ACTIVE PATTERN CONTINUES.
THE UPPER TROUGH ASSOCIATED WITH ALL THE WEATHER WEDNESDAY NIGHT
INTO FRIDAY WILL PASS ACROSS THE AREA VERY EARLY SATURDAY.  THEN
ANOTHER STORM SYSTEM IS MODELED TO SWING THROUGH LATER SATURDAY INTO
SUNDAY.  THIS WILL START OUT WITH RATHER HIGH SNOW LEVELS TO START
WITH THEN DROP INTO SUNDAY.  THERE IS ALSO THE POTENTIAL FOR SOME
DECENT WINDS WITH THIS STORM.  THE PARADE OF STORMS LOOKS TO
CONTINUE WITH ANOTHER SYSTEM EXPECTED SOMETIME MONDAY.  AT THIS TIME
RANGE THE DETAILS AND TIMING ARE UNDER QUESTION...HOWEVER THE IDEA
OF REPETITIVE SYSTEMS AFFECTING WESTERN WASHINGTON LOOKS RATHER
SOLID IN THE MODELS...SO MORE OF THE SAME INTO NEXT WEEK.  CERNIGLIA

&&

.HYDROLOGY...FLOOD WARNING AND WATCHES REMAIN IN EFFECT FOR PORTIONS
OF WESTERN WASHINGTON. MINOR FLOODING EXPECTED ALONG THE PUYALLUP
NEAR ORTING THIS MORNING BASED ON LATEST DATA. HEAVY PRECIP NOT
EXPECTED TODAY.

PREVIOUS DISCUSSION...STEADY RAIN WILL COME TO AN END BEFORE SUNRISE
AS A COLD FRONT MOVES THROUGH WESTERN WASHINGTON. FLOOD WARNINGS AS
OF 11Z ARE IN EFFECT FOR THE SATSOP AND SKOKOMISH RIVERS...AS WELL
AS THE STILLAGUAMISH AT ARLINGTON. OUT OF THESE THREE RIVERS ONLY
THE SKOKOMISH WILL BE ABOVE FLOOD STAGE TONIGHT.

THE FLOOD WATCH FOR MULTIPLE COUNTIES IN WESTERN WASHINGTON WILL BE
DROPPED LATER THIS MORNING FOR MOST COUNTIES. THE ONLY COUNTIES LEFT
IN THE WATCH WILL BE LEWIS...THURSTON AND GRAYS HARBOR. THE UPPER
REACHES OF THE CHEHALIS WILL CREST THIS MORNING JUST BELOW FLOOD
STAGE. THE CREST WILL MOVE DOWNSTREAM LATER TODAY AND TOMORROW
REACHING GRAYS HARBOR ON THURSDAY. MINOR FLOODING IS STILL POSSIBLE
ON THE CHEHALIS AS THE CREST MOVES DOWNSTREAM.

THE FLOOD WARNING FOR SMALL STREAMS IN CLALLAM...JEFFERSON...MASON
AND GRAYS HARBOR COUNTY WILL ALSO COME TO END LATER TODAY AS WATER
LEVELS RECEDE.

THE NEXT THREAT FOR SIGNIFICANT RAINS WILL BE WEDNESDAY NIGHT
THROUGH FRIDAY AS A SERIES OF SYSTEMS RIPPLE UP A BAROCLINIC BAND
THAT WILL BE SITTING ACROSS THE AREA IN SW FLOW ALOFT.  THIS WILL
GENERATE PULSES OF RAINFALL/SNOWFALL AS THE FREEZING LEVEL WILL BE
FLUCTUATING AS EACH SYSTEM PASSES THROUGH.  THE OLYMPICS WILL TAKE
THE BRUNT OF THIS ONCE AGAIN WITH THE NORTHERN CASCADES COMING IN
SECOND.  AT THIS POINT IT DOES NOT LOOK AS HEAVY AS THIS ROUND WAS
BUT RIVERS ACROSS THE OLYMPICS WILL STILL BE RUNNING FAIRLY HIGH AND
COULD PUSH FLOOD STAGE AGAIN...ESPECIALLY THE SKOKOMISH.  WILL
GREATLY DEPEND ON THE SNOW LEVEL.  THIS PATTERN IS NOT A FLOOD
PRODUCER FOR THE GREEN RIVER.

THE SYSTEMS EXPECTED THIS WEEKEND AND EARLY NEXT WEEK ARE EXPECTED
TO BE MORE PROGRESSIVE WITH LIGHTER AMOUNTS THUS FLOODING IS MUCH
LESS LIKELY.  CERNIGLIA

&&

.AVIATION...A COLD FRONT OVER THE CASCADES IS WEAKENING AS IT MOVES
EAST. SW FLOW ALOFT WILL CONTINUE OVER W WA AS A UPPER LEVEL TROUGH
OFFSHORE APPROACHES THE AREA...THEN MOVES INLAND OVER W WA AFTER
06Z. AIR MASS WILL BECOMING UNSTABLE WITH SHOWERS AND A CHANCE OF
THUNDERSTORMS INCREASING AS THE UPPER LEVEL TROUGH APPROACHES THIS
AFTERNOON. SW FLOW ALOFT SHOULD MAINTAIN MOUNTAIN OBSCURATION OVER
THE CASCADES. MOST AREAS VFR THIS MORNING BUT JUST A FEW POCKETS OF
MVFR. EXPECT VFR TO CONTINUE TODAY...WITH BRIEF MVFR CIGS/VIS AROUND
SHOWERS. CHANCE OF THUNDERSTORMS IS HIGHEST ALONG THE COAST...WITH
ONLY ISOLATED BRIEF ACTIVITY INLAND...PROBABLY ONE-CLAP WONDERS AT
BEST.

KSEA...S-SW WINDS 7 TO 15 KT TO CONTINUE TODAY. CONDITIONS MAINLY
VFR...BUT BRIEFLY MVFR CIGS ARE PROBABLE AROUND SHOWERS. AIR MASS IS
BECOMING UNSTABLE...BUT THE CHANCE OF THUNDERSTORMS IS TOO SMALL TO
INCLUDE IN THE TAF. KAM

&&

.MARINE...WITH THE SURFACE NOW UP OVER CENTRAL B.C. AND PROBABLY AT
AROUND 983 MB...PRESSURE GRADIENTS HAVE BEEN WEAKENING ACROSS W WA.
LATEST OBS SHOW THAT THE LAST COUPLE OF SPOTS HAVE DROPPED BELOW
GALE FORCE...SO WILL END THE GALES WITH THE 9 AM UPDATE. EXPECT
WINDS TO TRANSITION SLOWLY THROUGH SCA FOR SOME AREAS WITH ALL
INLAND AREA WINDS BELOW SCA BY THIS EVENING...FOR A SHORT TIME. WILL
KEEP THE COAST WINDS UP AT SCA EVEN THOUGH THERE MAY BE A BRIEF
PERIOD OVERNIGHT WHERE THEY DROP BELOW. NEXT SYSTEM IS OUT NEAR 160W
AND JUST S OF THE ALEUTIANS...AND SHOULD BEGIN AFFECTING THE AREA
WEDNESDAY AFTERNOON. GFS HAS THE NEXT SURFACE LOW GOING IN OVER THE
QUEEN CHARLOTTES AT AROUND 975 MB...COMPARED TO THIS LAST SYSTEMS
LOW THAT CROSSED QUEEN CHARLOTTE SOUND AT 982 MB. SO THIS NEXT
SYSTEM MAY BE CLOSE IN STRENGTH TO THE PREVIOUS ONE. GALE WATCH IS
ALREADY UP...BUT WILL HAVE TO MULL OVER POTENTIAL STORM FORCE WINDS
FOR THE COAST AND WEST ENTRANCE...THOUGH HIGH END GALES STILL LOOK
GOOD FOR THE INLAND WATERS.

BUOYS SHOW SEAS ON THE COAST A LITTLE BELOW 20 FEET AND PRESSURE AT
1008 MB...A LITTLE HIGHER THAN EXPECTED. THUS THE COASTAL FLOOD
ADVISORY FOR MINOR TIDAL OVERFLOW ALONG THE COAST IS LOOKING
MARGINAL AT BEST. WILL STILL LEAVE IT UP...THEN PROBABLY END IT WITH
THE AFTERNOON PACKAGE. LIKEWISE...SHOULD BE ABLE TO DROP THE HIGH
SURF ADVISORY AS WELL. KAM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WATCHES AND WARNING ACROSS PORTIONS OF WESTERN WA.
    .HIGH SURF ADVISORY IN EFFECT FOR THE NORTH AND CENTRAL COAST.
    .COASTAL FLOOD ADVISORY IN EFFECT FOR THE CENTRAL COAST.

PZ...SMALL CRAFT ADVISORY COAST...WEST AND CENTRAL STRAIT...NORTH
      INLAND WATERS AND PUGET SOUND AND HOOD CANAL.
    .SMALL CRAFT ADVISORY GRAYS HARBOR FOR ROUGH TO SEVERE BAR
     CONDITIONS.
    .GALE WATCH FOR COASTAL WATERS...ENTRANCES TO THE STRAIT...
     ADMIRALTY INLET...NORTHERN INLAND WATERS FOR WEDNESDAY
     AFTERNOON AND NIGHT.

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