FXUS66 KSEW 282251
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
250 PM PST SAT NOV 28 2009
.SYNOPSIS...A WARM FRONT OVER THE REGION WILL CONTINUE TO BRING A
THREAT OF LIGHT PRECIPITATION TO THE AREA INTO SUNDAY MORNING AS IT
SLOWLY LIFTS NORTHWARD. A WEAK COLD FRONT WILL BRUSH THROUGH THE
REGION LATE MONDAY THEN AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL
BE IN CONTROL OF OUR WEATHER DURING THE MIDDLE OF THE WEEK.
&&
.SHORT TERM...LIGHT RAIN HAS BEEN FALLING ALONG THE COAST AND ACROSS
THE NORTH THROUGH THE DAY TODAY AND HAS MADE A BIT OF PROGRESS INTO
THE INTERIOR THANKS TO WARM ADVECTION ALOFT. THIS WILL CONTINUE
WELL INTO THE NIGHT THEN THE AREA OF WARM ADVECTION WILL LIFT NORTH
TONIGHT INTO SUNDAY TAKING THE PRECIPITATION WITH IT. AS THE FRONT
LIFTS NORTH SUNDAY...WARMER AIR WILL FILTER IN AND THE CLOUDS SHOULD
DIMINISH. THIS DIMINISHING IN CLOUDS COULD BRING ABOUT A DECENT
AMOUNT OF FOG ESPECIALLY SINCE THE SURFACE GRADIENTS WILL BE WEAK.
A RELATIVELY WEAK COLD FRONT IS STILL EXPECTED TO SWEEP SOUTHEAST
ACROSS THE AREA LATER MONDAY FOR A THREAT OF A FEW SHOWERS AND AN
ENHANCEMENT OF THE CLOUD COVER. THIS FRONT WILL SWEEP COOLER AND
DRIER AIR INTO THE AREA BUT THE COOL PART...MAINLY UPPER
LEVELS...WILL NOT LAST LONG AS AN UPPER RIDGE WILL BUILD IN ITS WAKE
TUESDAY FOR DRY WEATHER WITH SOME SUNSHINE. WE WILL HAVE SEASONAL
TEMPERATURES THROUGH THE PERIOD. CERNIGLIA
.LONG TERM...AT LEAST THROUGH WEDNESDAY WE WILL BE UNDER THE
INFLUENCE OF THE UPPER RIDGE AND SO WILL REMAIN DRY AND PARTLY
CLOUDY. BEYOND THAT...THINGS GET REAL FUZZY IN THE MODEL WORLD AND
CONFIDENCE IS RATHER LOW IN THE DETAILS OF THE FORECAST. NONE OF
THE SOLUTIONS ARE VERY WET...BUT NOT DRY EVERY DAY EITHER. THE
VARIANCE IN THE MODELS IS RATHER STRIKING OUT OVER THE PACIFIC WHICH
OF COURSE AFFECT OUR WEATHER. AT THIS POINT WE...ALL THE OFFICES IN
THE NORTHWEST...DECIDED TO INTRODUCE A SLIGHT CHANCE OF
PRECIPITATION...STILL WELL BELOW CLIMATOLOGY...INTO THE FORECAST
WITH A BIT OF ADDITIONAL CLOUDS FOR THE THURSDAY ONWARD TIMEFRAME.
WE WILL HAVE TO SEE HOW THIS PLAYS OUT. CERNIGLIA
&&
.HYDROLOGY...VERY LIGHT PRECIPITATION OVER THE NEXT COUPLE OF DAYS
WILL HAVE NO AFFECT ON AREA RIVERS AND THEN THE FORECAST IS FOR DRY
WEATHER THROUGH MIDWEEK.
EVEN THOUGH THERE IS SIGNIFICANT VARIANCE IN THE LONG RANGE MODELS
FOR LATE NEXT WEEK AND NEXT WEEKEND...NONE OF THE SOLUTIONS ARE GOOD
FOR HEAVY PRECIPITATION. THEREFORE NO FLOODING PROBLEMS ANTICIPATED
THROUGH NEXT WEEKEND.
NO FLOODING IS EXPECTED ON THE GREEN RIVER THROUGH NEXT WEEK.
CERNIGLIA
&&
.AVIATION...NORTHWEST FLOW ALOFT BACKING TO WESTERLY SUN. WEAK UPPER
RIDGE AND SFC HIGH PRES WILL SHIFT OVR WA THRU TNGT AS A WARM FRONT
MOVES INTO B.C. CLIPPING WRN WA THRU TNGT. SOME AREAS OF LOW CIGS
WITH LIGHT RAIN OR DRIZZLE TNGT AND SUN MORNING. AIR MASS WILL
REMAIN STABLE WITH LOW LEVEL MOISTURE THRU SUN MORNING...THEN
PARTIAL CLEARING. A GOOD CHANCE THAT AREAS OF FOG DEVELOP SUN
NITE.
KSEA...SOUTHERLY WIND DIMINISHING OVERNIGHT. CIGS SHUD LOWER
OVERNIGHT WITH A CHANCE OF 3-5SM -DZ...THEN A CHANCE FOR PARTIAL
CLEARING SUN AFTERNOON AND EVENING...WHICH COULD LEAD TO SOME FOG
SUN NITE AS WINDS POSSIBLY GO CALM.
&&
.MARINE...A WARM FRONT MOVG INTO BRITISH COLUMBIA THRU TNGT WITH THE
SOUTHERN PTN BRUSHING WRN WA. SMALL CRAFT ADVISORY WINDS ALL WATERS
XCP CENTRAL STRAIT BUT DIMINISHING OVERNIGHT AS GRADIENTS RELAX AND
WEAK HIGH PRES BUILDS IN. A COLD FRONT WILL CLIP WRN WA MON THEN
HIGH PRESSURE WILL BUILD OVR BRITISH COLUMBIA THRU MONDAY NIGHT AND
TUE PROVIDING OFFSHORE FLOW ACROSS WESTERN WASHINGTON.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR ROUGH BAR CONDITIONS GRAYS HARBOR.
.SMALL CRAFT ADVISORY COASTAL WATERS...ENTRANCES TO THE
STRAIT OF JUAN DE FUCA...ADMIRALTY INLET...NORTHERN INLAND
WATERS...PUGET SOUND AND HOOD CANAL.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
