FXUS66 KSEW 271656
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 AM PST FRI NOV 27 2009
.SYNOPSIS...DRY WEATHER WILL PREVAIL OVER THE AREA THIS AFTERNOON
UNDER HIGH PRESSURE ALOFT. A WEAK SYSTEM PASSING TO OUR NORTH WILL
GIVE THE REGION A THREAT OF LIGHT PRECIPITATION TONIGHT THROUGH
SATURDAY NIGHT. BUILDING HIGH PRESSURE ALOFT WILL THEN BRING DRY
WEATHER BACK TO THE AREA ON SUNDAY...WHICH WILL CONTINUE INTO NEXT
WEEK.
&&
.SHORT TERM...SKIES ARE CLEARING OUT NICELY MOST AREAS IN THE WAKE
OF THE THE SYSTEM THAT AFFECT THE REGION THROUGH LAST NIGHT. SO A
DECENT AMOUNT OF SUNSHINE TODAY THEN MID AND HIGH CLOUDS WILL SPREAD
EAST ACROSS WESTERN WASHINGTON TONIGHT.
THE HIGHER CLOUDS ARE THE ADVANCE NOTICE THAT WARM ADVECTION IS
BEGINNING TO TAKE HOLD AND WHICH WILL STRENGTHEN SATURDAY WITH
ADDITIONAL MOISTURE. AS A RESULT WE HAVE SOME RAIN...SNOW IN THE
MOUNTAINS...SATURDAY INTO SATURDAY NIGHT. THE THREAT WILL BE
GREATEST OVER NORTHERN AREAS WHILE THE FAR SE PART OF OUR FORECAST
AREA...CENTRAL AND EASTERN LEWIS COUNTY...COULD END UP DRY THROUGH
THIS EVENT. AMOUNTS WILL BE LIGHT WHERE IT DOES RAIN AND SNOW
AMOUNTS WILL RANGE FROM A INCH SOUTH TO MAYBE A FOOT OVERALL AT MT
BAKER. I WILL HAVE TO LOOK INTO THIS MORE THIS AFTERNOON.
THIS WHOLE AREA OF WARM ADVECTION WILL LIFT NORTH THROUGH SUNDAY
DIMINISHING THE THREAT OF PRECIPITATION AND ALLOWING THE CLOUDS TO
THIN OUT. CERNIGLIA
.LONG TERM...A MAJOR AND LIKELY WELCOME CHANGE IN THE WEATHER
PATTERN BEGINS TO TAKE SHAPE MONDAY. A WEAK COLD FRONT IS EXPECTED
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. CERNIGLIA
&&
.HYDROLOGY...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 ANY 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.
CERNIGLIA
&&
.AVIATION...CLEAR SKIES ACROSS A GOOD PART OF WRN WA AS HIGH PRES
BUILDS OVER THE AREA. THERE ARE A FEW AREAS OF CLOUDS...FROM THE SRN
OLYMPICS SOUTH AND THE WEST SLOPES OF THE CASCADES AND SKAGIT AND
MOST OF SNOHOMISH COUNTY AT 830 AM. AIR MASS IS FAIRLY DRY TODAY BUT
WILL MOISTEN UP TNGT AHEAD OF FRONT THAT WILL MOSTLY MOVE INTO B.C.
SAT MORNING. NLY FLOW ALF BECMG NW. AMS MOIST AND STABLE WITH AREAS
OF LIGHT RAIN BY DAYBREAK SAT WITH THE WMFNT BRUSHING WRN WA. 19
KSEA...NLY BREEZE TODAY AND SCATTERED CLOUDS...SE FLOW DVLPG
OVERNIGHT TONIGHT WITH INCREASING CLOUDS AND A LOW CIG DRIPPY DAY ON
TAP FOR SAT WITH SLY 10-20KT WIND.
&&
.MARINE...NW BREEZE DECREASING THRU THE DAY THEN BACKING TO SLY
OVERNIGHT. A GOOD 25KT SLY SMALL CRAFT ADVISORY DAY WITH RAIN AT
TIMES SATURDAY AS THE WARM FRONT ARRIVES...STRONGEST WINDS WILL BE
COAST AND SAN JUANS SATURDAY...POSSIBLY PUSHING 30KT IN A FEW SPOTS.
PUGET SOUND MAY GET BY WITH 15-20KT SAT AND NO SMALL CRAFT...FCSTS
LOOK FINE. AFTER THE WARM FRONT HIGH PRES WILL BUILD OVER THE
REGION...THRU SUN NIGHT THE SFC HIGH IS INLAND GVG LIGHT ELY FLOW
AND THEN BY TUE THE GFS IS SHOWS THE HIGH CENTERED UP NEAR THE B.C.
ALTA BORDER GIVING NE FLOW OVER WRN WA. 19
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.
SMALL CRAFT ADVISORY COASTAL WATERS AND WEST ENTRANCE...AND
UNTIL 1 PM FOR THE EAST ENTRANCE NORTHERN WATERS AND
ADMIRALTY.
SMALL CRAFT ADVISORY FOR ROUGH BAR CONDITIONS GRAYS HARBOR BAR.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
