000
FXUS66 KSEW 042125
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 PM PDT SAT SEP 4 2010
.SYNOPSIS...AN UPPER TROUGH OVER THE PACIFIC NORTHWEST WILL MOVE
INLAND SUNDAY. ANOTHER WEATHER SYSTEM WILL AFFECT WESTERN WASHINGTON
MONDAY AND TUESDAY. THE WEATHER PATTERN WILL REMAIN UNSETTLED INTO
NEXT WEEKEND.
&&
.SHORT TERM...THE 4KM WRFGFS HAS SOME SHOWER ACTIVITY REDEVELOPING
LATER THIS EVENING...THE SHOWERS THE MODEL HAS ALONG THE COAST SEEM
THE LEAST LIKELY WHILE THE ACTIVITY THE MODEL HAS FROM ADMIRALTY
INLET SE THRU THE METRO AREA AND INTO THE CASCADES SEEMS THE MOST
PROMISING CONSIDERING THE AREAS OF DRIZZLE THIS MORNING THAT
DEVELOPED MNLY KING AND SNOHOMISH COUNTY. MANY AREAS ARND WRN WA HAD
QUITE A BIT OF SUNSHINE TODAY...AREAS OUTSIDE THE PSCZ...AND SUNDAY
SHOULD BE A REPEAT OF THAT AS THE WLY FLOW ALF TDY TURNS TO NNW. THE
NEXT WEATHER SYSTEM BRINGS SHOWERS TO THE AREA FOR MON AND
TUE...WITH THE LATEST NAM SHOWING PCPN ARRIVING NW HALF OF WRN WA BY
12Z MON. SHOWERS ARE A GOOD BET AT TIMES THRU TUESDAY AS A 557DM
LOW WORKS SOUTH ALONG THE B.C. COAST AND...IF THE EURO MODEL IS
RIGHT...IS STILL ONLY CENTERED OVER ASTORIA 00Z WED. THE GFS AND
EARLIER RUNS HAD MORE OF THE TROF SINKING FASTER INTO CALIF BY LATE
TUE. 19
.LONG TERM...THE EXTENDED PERIOD IS LIKELY TO REMAIN COOL WITH A
CHANCE OF SHOWERS FROM TIME TO TIME. THE GLOBAL MODELS KEEP A WEAK
WEST COAST TROF IN PLACE. THE 12Z MODELS DO NOT LOOK AS WET AS
PREVIOUS RUNS...NUISANCE SHOWERS...BUT THE PATTERN IS UNCHANGED.
ESPECIALLY BY LATE NEXT WEEKEND IN THE EURO THE RIDGE AXIS AT 155W
GAINS SOME AMPLITUDE AND ANOTHER 550DM LOW SINKS SOUTH ALONG
130W...THE 06Z GFS WAS SIMILAR WHILE THE 12Z GFS IS RATHER WEAK. 19
&&
.AVIATION...AN UPPER TROUGH OVER EASTERN WASHINGTON WILL SHIFT
FARTHER INLAND TONIGHT WITH NORTHWEST FLOW. AT THE SURFACE HIGH
PRESSURE WILL BE OFFSHORE WITH LOWER PRESSURE INLAND. LOW LEVEL
MOISTURE OVER THE CASCADES AND CENTRAL PUGET SOUND WILL EXPAND TO
MOST OF WESTERN WASHINGTON BY SUNDAY MORNING.
MODELS SUGGEST CONVERGENCE ZONE WILL REFORM AGAIN OVER THE CENTRAL
PUGET SOUND THIS EVENING AND PERSIST MOST OF THE NIGHT. NOT TOO SURE
IF THIS WILL PAN OUT BUT HAVE LEANED THIS WAY IN THE CENTRAL PUGET
SOUND TAFS.
KSEA...LOW CLOUDS MAY SCATTER FOR A FEW HOURS EARLY THIS EVENING.
CLOUDS SHOULD THEN FILL BACK IN TONIGHT AND LOWER. POSSIBLE REDUCED
VISIBILITIES WITH A CONVERGENCE ZONE AS WELL. SOUTHWEST WIND 4-8KT.
SCHNEIDER
&&
.MARINE...MODERATE ONSHORE FLOW THIS EVENING WILL RESULT IN ANOTHER
WESTERLY GALE IN THE CENTRAL/EAST STRAIT. SMALL CRAFT ADVISORY WINDS
EXPECTED MOST OTHER WATERS TONIGHT AS WELL.
THE ONSHORE FLOW WILL RELAX A BIT SUNDAY AS A WEAK FRONTAL SYSTEM
APPROACHES THE OFFSHORE WATERS. THE FRONTAL SYSTEM WILL MOVE INTO
THE COASTAL WATERS MONDAY THEN BREAK UP. ONSHORE FLOW WILL INCREASE
AGAIN TUESDAY AND WEDNESDAY WITH HIGH PRESSURE OFFSHORE AND LOWER
PRESSURE INLAND. SCHNEIDER
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...GALE WARNING CENTRAL AND EAST STRAIT.
SMALL CRAFT ADVISORY COASTAL WATERS...WEST ENTRANCE...ADMIRALTY
INLET...AND NORTHERN INLAND WATERS.
$$
WWW.WEATHER.GOV/SEATTLE
NWS SEW Office Area Forecast Discussion
| 
