Napavine Weather Discussion

000
FXUS66 KSEW 291547
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 AM PDT THU JUL 29 2010

.SYNOPSIS...A SURFACE HIGH OVER THE NORTHEAST PACIFIC COMBINED WITH
LOWER PRESSURE EAST OF THE CASCADES WILL MAINTAIN ONSHORE FLOW
ACROSS WESTERN WASHINGTON FOR THE NEXT WEEK. THIS WILL CONTINUE THE
PATTERN OF LATE NIGHT AND MORNING LOW CLOUDS WITH AFTERNOON CLEARING
IN THE INTERIOR. THERE WILL BE A CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS IN THE CASCADES...MAINLY NEAR THE CREST.

&&

.SHORT TERM...A FEW AREAS OF DRIZZLE THIS MORNING SO ADDED THAT TO
THE ZONES...THE STRATUS IS A NOTCH DEEPER SO SHUD BE SLOWER TO BURN
OFF TODAY. MOST OF THE CASCADES AND OLYMPICS ARE UP IN THE SUN. WITH
MORNING DRIZZLE AT WHIDBEY THE STRATUS MAY BE THE DEEPEST FROM THERE
EAST THRU SNOHOMISH COUNTY...AND IT WOULDN`T SURPRISE ME TO SEE THE
AFTERNOON SATELLITE IMAGE SHOW AN AREA OF PERSISTENT PSCZ
CLOUDS...BUT EVEN THAT AREA OUGHT TO BURN OFF BY MID AFTERNOON. THE
FCST FOR MORNING CLOUDS EACH DAY LOOKS GOOD. THERE ARE HOLES IN THE
STRATUS JUST OFFSHORE THIS MORNING SO THE COAST MIGHT SEE A BIT MORE
SUN TODAY...BUT MOSTLY CLOUDY IS A GOOD FCST EACH DAY AND THERE
REALLY ISN`T ANY SIGN OF THIS PATTERN BECOME MORE SUMMERY OVER THE
NEXT WEEK. 19

.LONG TERM...ALL LONG TERM MODELS INCLUDING THE GFS...ECMWF...AND
CANADIAN SHOW ANOTHER UPPER LOW DEVELOPING INTO THE AREA EARLY NEXT
WEEK. SUBTLE AND ALL IMPORTANT CHANGES IN THE STRENGTH OF THE
ONSHORE FLOW AND THE DEPTH OF THE MARINE LAYER WILL IMPACT THE
WEATHER FOR THE NEXT SEVERAL DAYS...BUT WILL BE DIFFICULT TO
FORECAST BEYOND A DAY OR TWO OUT. THUNDERSTORMS CANNOT BE RULED OUT
OVER THE CASCADES DURING THE AFTERNOON HOURS WITH A TROUGH SITTING
JUST OFFSHORE. AT THIS POINT WILL OPT FOR A PERSISTENCE FORECAST.
ALBRECHT

&&

.AVIATION...SOUTHWEST FLOW ALOFT OVER WESTERN WASHINGTON AHEAD OF AN
UPPER LEVEL TROUGH OFFSHORE ALONG 130W. WEAK ONSHORE FLOW CONTINUES
AT LOW LEVELS. CLOUDY MARINE LAYER COVERS WESTERN WASHINGTON THIS
MORNING WITH TOPS AROUND 2500 FT. THE AIR MASS WILL BECOME WEAKLY
UNSTABLE OVER THE CASCADES DURING THE AFTERNOON AND EVENING HOURS.

WIDESPREAD IFR AND LOW-END MVFR CONDITIONS ACROSS WESTERN WASHINGTON
THIS MORNING DUE TO ONSHORE FLOW AND MARINE LAYER OVER THE AREA. THE
CLOUDS SHOULD SCATTER OUT AND GIVE WAY TO VFR CONDITIONS 19Z-21Z.
CLOUDS WILL FROM IN THE MARINE LAYER AGAIN TONIGHT 10Z-12Z.

KSEA...SOUTHWEST WIND 3-6 KT BECOMING NORTHWEST 4-8 KT LATE THIS
AFTERNOON...THEN BACKING TO SOUTHWEST AGAIN LATE THIS EVENING.
CEILING OVC005 THIS MORNING WITH TOPS 025...BECOMING SCT-BKN 18Z-19Z
AND THEN CLEARING 20Z-21Z. MCDONNAL

&&

.MARINE...SURFACE HIGH PRESSURE OFFSHORE AND LOWER PRESSURE EAST OF
THE CASCADES WILL PROVIDE CONTINUING ONSHORE FLOW THROUGH EARLY NEXT
WEEK. DAYTIME HEATING WILL CAUSE THE STRONGEST WINDS TO OCCUR EACH
DAY DURING THE LATE AFTERNOON AND EVENING HOURS...WITH SMALL CRAFT
ADVISORY WINDS LIKELY IN THE CENTRAL STRAIT OF JUAN DE FUCA AND EAST
ENTRANCE. MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE CENTRAL AND
     EASTERN STRAIT OF JUAN DE FUCA THROUGH TONIGHT.

$$

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