FXUS66 KSEW 221750
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
910 AM PST SUN NOV 22 2009

.SYNOPSIS...A LOW PRESSURE CENTER OVER WASHINGTON WILL SHIFT INLAND 
AND HIGHER PRESSURE WILL BUILD INTO THE REGION TODAY. THIS WILL GIVE 
RATHER BLUSTERY WINDS...ESPECIALLY ON THE COAST AND IN THE STRAIT OF 
JUAN DE FUCA. SNOW SHOWERS WILL BE HEAVY AT TIMES IN THE MOUNTAINS. 
A WARM FRONT WILL MOVE THROUGH THE AREA MONDAY AND MONDAY 
NIGHT...FOLLOWED BY ANOTHER WARM FRONTAL SYSTEM LATER IN THE WEEK. 
&&

.SHORT TERM...ANOTHER BLUSTERY DAY FOR WRN WA...WINDY ON THE COAST 
AND THRU THE CHEHALIS GAP...AND WESTERLY GALES SHUD DVLP IN THE 
STRAIT BY NOON. THE WIND ADVISORY SHUD PROBABLY BE EXTENDED NORTH 
THRU THE METRO AREA AND HOOD CANAL FOR RATHER BLUSTERY WEATHER DVLPG 
THRU THE MORNING AND PEAKING MIDDAY. WHEN I DO THAT I WILL HAVE THEM 
ALL EXPIRE AT 3PM. SHOULD BE A GOOD PSCZ WIND PATTERN BY 
AFTERNOON...SO AFTER THE SURGE OF SW 20-30MPH WINDS THIS MORNING 
THRU THE SEATTLE METRO AREA THE WIND WILL SETTLE DOWN AS THE PSCZ 
SETS UP. THE WINTER STORM WARNING FOR THE CASCADES PROBABLY NEEDS A 
REFRESH AS WELL...IT EXPIRES AT 1PM AND AS THE WESTERLY OROGRAPHIC 
SNOW KICKS IN BY AFTERNOON SO THAT NEED TO BE EXTENDED INTO THE 
EARLY EVENING. WINDS IN THE CASCADE PASSES INCREASING TO WESTERLY 
20-30 MPH BY AFTERNOON AND GUSTS TO 50 ON THE RIDGETOPS...A LOT LESS 
THAN THE PEAK WINDS OVERNIGHT: AT THE VERY TOP OF CRYSTAL MOUNTAIN 
ARND 1AM LAST NITE STRONG SE WINDS OF 50 MPH GUSTED TO ARND 
95MPH...QUITE A WINTER STORM UP HIGH. THE SYSTEM FOR MONDAY WILL BE 
WEAKER AND WARMER...ALTHOUGH IT WILL PROBABLY MUSTER SSE GALES JUST 
AHEAD OF THE FRONT OVER THE COASTAL WATERS MON MORNING....BY MON 
NITE THE GRADIENT OVER WRN WA IS QUITE LIGHT. IN FACT THE WEATHER 
PATTERN NEXT WEEK LOOKS A LOT LIKE WHAT EL NINO IS SUPPOSED TO 
BRING...WARMTH AND FAIRLY WEAK SYSTEMS. 19

.LONG TERM...ANOTHER WARM FRONT WILL BRUSH THE NORTHWEST CORNER OF 
THE AREA AS IT MOVES INTO BRITISH COLUMBIA. THE TRAILING COLD FRONT 
WILL DRAG SLOWLY ACROSS THE FORECAST AREA WEDNESDAY NIGHT THROUGH 
THURSDAY FOLLOWED BY ITS UPPER TROUGH THURSDAY NIGHT AND FRIDAY. 
MCDONNAL

&&

.HYDROLOGY...THE ONLY CURRENT RIVER FLOOD PROBLEM IS THE SKOKOMISH 
RIVER. IT IS JUST ABOVE FLOOD STAGE THIS MORNING AND WILL LIKELY 
REMAIN ABOVE FLOOD STAGE INTO MONDAY. THIS IS DUE PRIMARILY TO 
RELEASES OF WATER FROM CUSHMAN DAM #2. THE SYSTEM MOVING THROUGH 
WESTERN WASHINGTON TODAY IS NOT A FLOOD-PRODUCING RAIN SYSTEM BUT 
RATHER A HEAVY MOUNTAIN SNOW SYSTEM. 

THE FRONTAL SYSTEMS EXPECTED TO ARRIVE DURING THE COMING WEEK WILL 
BE ACCOMPANIED BY HIGHER SNOW LEVELS -- PROBABLY IN THE 5000 TO 7000 
FT RANGE. ONE FRONT IS FORECAST TO MOVE THROUGH MONDAY AND MONDAY 
NIGHT WITH ANOTHER SYSTEM MOVING SLOWLY THROUGH WEDNESDAY NIGHT 
THROUGH THURSDAY NIGHT. THEY ARE NOT EXPECTED TO PRODUCE ENOUGH 
PRECIPITATION TO CREATE FLOODING CONCERNS.

NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER. 

&&

.AVIATION...SURFACE LOW PRES THAT MOVED ONSHORE EARLIER THIS MORNING 
IS NOW SHIFTING INTO WRN WA ALONG WITH THE UPPER TROUGH. ONSHORE 
FLOW WILL PERSIST TODAY WITH STRONG WLY FLOW ALOFT. THE ATMOSPHERE 
WILL REMAIN MOIST AND SLIGHTLY UNSTABLE THIS MORNING WITH WRAP 
AROUND MOISTURE KEEPING LOWER CIGS AND RAIN AROUND A LITTLE LONGER 
THAN EXPECTED. CIGS SHOULD IMPROVE TO VFR AFTER 21Z WITH DECREASING 
MOISTURE. WITH PARTIAL CLEARING TONIGHT...EXPECT AREAS OF FOG TO 
FORM...MOSTLY IN FAVORED SHELTERED VALLEYS. 

A PUGET SOUND CONVERGENCE ZONE /PSCZ/ WILL DEVELOP N OF THE 
SNOHOMISH/KING COUNTY BORDER LATER THIS MORNING AND THEN MOVE S 
DURING THE AFTERNOON...BECOMING QUASISTATIONARY OVER THE N CENTRAL 
PUGET SOUND. AT THIS TIME...IT LOOKS LIKE THE PSCZ WILL REMAIN N OF 
KBFI. WINDS WILL BACK TONIGHT AS THE PRES GRADIENT BECOMES SLY... 
THUS EXPECT THE PSCZ TO DRIFT BACK TO THE N AND THEN DISSIPATE LATER 
TONIGHT. 

KSEA...CIGS 1-2K FT AND VIS 3-5SM MAY HOLD IN A LITTLE LONG THAN 
EXPECTED DUE TO WRAP AROUND MOISTURE. STILL EXPECT IMPROVEMENT TO 
VFR CONDITIONS BY 21Z. SW WIND 10-15 KT W/ GUSTS TO 30 KT 
TODAY...BECOMING S 3-6 KT THIS EVENING. DTM

&&

.MARINE...STRONG ONSHORE FLOW TODAY BEHIND A LOW PRESSURE SYSTEM 
WHICH IS NOW SHIFTING INTO ERN WA. GALES ALONG THE COAST SHOULD 
CONTINUE THROUGH MOST THE DAY BEFORE EASING. THE WINDS IN THE STRAIT 
TOOK A LITTLE LONGER THAN EXPECTED TO COME AROUND WLY...BUT SHOULD 
STILL POP UP TO GALE FORCE BY NOON. WINDS HAVE COME UP SLIGHTLY 
AROUND PUGET SOUND BUT OBS SO FAR ARE FAR SHORT OF GALES...SO I WILL 
KEEP A SMALL CRAFT IN EFFECT TODAY. DTM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...A FLOOD WARNING REMAINS IN EFFECT FOR THE SKOKOMISH RIVER
     IN MASON COUNTY.

     A WINTER STORM WARNING REMAINS EFFECT FOR THE CASCADES TODAY.

     WIND ADVISORIES ARE IN EFFECT FOR THE STRAIT OF JUAN DE FUCA
     AND THE ADMIRALTY INLET AREAS...SOUTHWEST INTERIOR...LOWER
     CHEHALIS VALLEY...SEATTLE TACOMA BREMERTON METRO AREA...HOOD
     CANAL.


PZ...GALE WARNINGS ARE IN EFFECT FOR ALL WATERS EXCEPT PUGET SOUND   
     TODAY.
     SMALL CRAFT ADVISORY PUGET SOUND TODAY.
     A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ROUGH GRAYS
     HARBOR BAR CONDITIONS TIL 4 PM MON.
   
$$

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Issued: 11/22/2009 2:01:39 PM

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