FXUS66 KSEW 270521
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
920 PM PST THU NOV 26 2009

.SYNOPSIS...A WEAK FRONT WILL REMAIN JUST SOUTH OF THE AREA WHILE AN 
UPPER TROUGH MOVES ACROSS THE REGION EARLY FRIDAY MORNING.  THE 
SOUTHERN END OF A WARM FRONT WILL APPROACH THE NORTHWEST FRIDAY 
NIGHT BRINGING A THREAT OF RAIN INTO SUNDAY.  A WEAK COLD FRONT WILL 
DROP SOUTHEAST THROUGH THE AREA MONDAY.  BEHIND THIS FRONT AN UPPER 
LEVEL RIDGE WILL BUILD OVER THE EASTERN PACIFIC TUESDAY FOR WHAT 
LOOKS TO BE THE BEGINNING OF AN EXTENDED PERIOD OF DRY WEATHER. 

&&

.SHORT TERM...STEADY LIGHT TO MODERATE RAIN STILL FALLING ACROSS THE 
CENTRAL AND SOUTHERN PORTIONS OF THE AREA THIS EVENING. KATX RADAR 
SHOWS RAIN ROUGHLY SOUTH OF A LINE FROM HOQUIAM TO EVERETT. THE 
SURFACE LOW IS NOW SHIFTING INTO CENTRAL ORE WITH PRES AROUND 1012 
MB...FAIRLY WEAK ALTHOUGH ENOUGH OF A NLY PRES GRAD TO CAUSE SCA 
WINDS IN PUGET SOUND/HOOD CANAL. THE RAIN BAND WILL SLOWLY SHIFT 
EAST/SOUTHEAST OVERNIGHT AS AN UPPER LEVEL TROUGH OFFSHORE MOVES 
INLAND. SHOULD NOT SEE ANY PROBLEMS WITH SNOW IN THE PASSES TONIGHT 
AS TEMPS ARE STILL ABOVE FREEZING WITH WA DOT REPORTS OF RAIN AND/OR 
FOG. 

A FEW SPRINKLES ARE POSSIBLE IN THE MORNING AROUND THE PUGET SOUND 
AREA AND FOOTHILLS/CASCADES...OTHERWISE DRY WEATHER ANTICIPATED AS A 
THE TROUGH DIGS SOUTH INTO CENTRAL CA...WITH RIDGING OVER WA. LOW 
LEVEL ONSHORE FLOW...MOIST BOUNDARY LAYER AND LITTLE MIXING WILL 
KEEP LOW CLOUDS ACROSS THE AREA. ANY SUN BREAKS WILL BE LATE AND 
BRIEF. 

ANOTHER WEAK WARM FRONT WILL GLANCE THE AREA ON SAT. RAIN TOTALS ARE 
LIGHT WITH JUST A FEW HUNDREDTHS IN THE INTERIOR AND UP TO A QUARTER 
INCH NORTH PART. AN UPPER LEVEL RIDGE MAY STRENGTHEN OVER THE PAC NW 
ON MON. 33

.LONG TERM...PREVIOUS DISCUSSION...A MAJOR AND LIKELY WELCOME CHANGE 
IN THE WEATHER PATTERN BEGINS TO TAKE SHAPE MONDAY.  A WEAK COLD 
FRONT IS FORECAST TO SLIDE SE ACROSS THE REGION OR POSSIBLY JUST 
BRUSH BY...THEN AN UPPER LEVEL RIDGE WILL BUILD OVER THE EASTERN 
PACIFIC AND THE WESTERN EDGE OF THE NORTH AMERICA.  AFTER THE WEAK 
FRONT MOVES BY...DRY WEATHER WILL TAKE HOLD TUESDAY AND LIKELY 
CONTINUE THROUGH AT LEAST THURSDAY AND ONE MODEL IS EVEN SUGGESTING 
IT MIGHT CONTINUE INTO NEXT WEEKEND.  WE ALREADY DRIED OUT THE 
FORECAST TUESDAY ONWARD YESTERDAY SO I JUST EXTENDED THAT TREND INTO 
THURSDAY.  CERNIGLIA 

&&

.HYDROLOGY...RAIN MAINLY AFFECTING THE CENTRAL CASCADES TONIGHT BUT 
SIGNIFICANT PRECIP ACCUMULATIONS ARE NOT EXPECTED. NO FLOOD CONCERNS 
ACROSS THE REGION.  

THE WARM ADVECTION SYSTEMS THAT WILL SPREAD LIGHT PRECIPITATION OVER 
WESTERN WASHINGTON THIS WEEKEND WILL BE RATHER WEAK AND AS A RESULT 
WILL NOT PRODUCE ENOUGH RAIN TO CAUSE ADDITIONAL RIVER PROBLEMS.  

BEYOND THAT THE FORECAST IS DRY WELL INTO NEXT WEEK AND LIKELY INTO 
THE FOLLOWING WEEKEND.  AS A RESULT NO NEW FLOODING IS EXPECTED 
THROUGH NEXT WEEK AND AREA RIVERS WILL RETURN TO LOWER FLOW LEVELS.  

NO FLOODING IS EXPECTED ON THE GREEN RIVER THROUGH NEXT WEEK.  
33/CERNIGLIA

&&

.AVIATION...A SURFACE LOW WILL MOVE ACROSS NORTHERN OREGON TONIGHT 
AND FILL...WITH ONSHORE SURFACE FLOW FOLLOWING. AN UPPER TROUGH WILL 
MOVE THROUGH FRIDAY MORNING. LIGHT FLOW ALOFT BECOMING NWLY. AIR 
MASS MOIST AND SLIGHTLY UNSTABLE. CEILINGS WILL FALL MOSTLY INTO THE 
LOW MVFR AND IFR CATEGORY TONIGHT. LOW CLOUDS AND FOG WILL HANG IN 
THROUGH AT LEAST MIDDAY FRIDAY.

KSEA...NE WIND 8-12 KT TONIGHT...SWINGING AROUND TO SW AFTER 21Z 
FRIDAY. CHB

&&

.MARINE...NORTHERLY WINDS REALLY KICKED IN OVER THE INLAND WATERS 
THIS EVENING AND HAD TO ISSUE A SMALL CRAFT ADVISORY FOR PUGET SOUND 
AND ADMIRALTY INLET. NORTHERLY GRADIENTS INCREASED AS A SURFACE LOW 
OFF OREGON MOVED ASHORE. THE LOW IS FORECAST TO FILL AND GRADIENTS 
WILL RELAX OVERNIGHT. SMALL CRAFT ADVISORY WINDS INLAND SHOULD BE 
DONE AROUND 09Z...BUT WILL CONTINUE ON THE COAST OFF AND ON THROUGH 
FRIDAY AFTERNOON. HEAVY SWELL ON THE COAST WILL ALSO CONTINUE... 
PROBABLY THROUGH FRIDAY NIGHT.

A WARM FRONT WILL BRUSH WESTERN WASHINGTON ON SATURDAY. THE BEST 
CHANCE FOR SMALL CRAFT ADVISORY CONDITIONS WILL BE OVER THE COASTAL 
WATERS. WINDS WILL COME UP ACROSS THE INTERIOR...POSSIBLY MARGINAL 
SMALL CRAFT WINDS AT THE ENTRANCES TO THE STRAIT AND MAYBE THE N 
INTERIOR. CHB

&&

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

PZ...SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.    
     SMALL CRAFT ADVISORY COAST...ADMIRALTY INLET...PUGET SOUND AND  
     HOOD CANAL.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS WEST ENTRANCE.

$$

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