Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 192230
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 PM PDT TUE MAY 19 2015

.SYNOPSIS...ONSHORE FLOW WILL CONTINUE THROUGH THE WEEKEND...
INCREASING A BIT TOWARD THE END OF THE WEEK. UNSTABLE AIR WILL
MAINTAIN A CHANCE OF AFTERNOON AND EVENING SHOWERS OR THUNDERSTORMS
OVER THE MOUNTAINS EACH DAY.

&&

.SHORT TERM...THE MARINE CLOUDS HAVE BURNED OFF FROM THE INTERIOR OF
WESTERN WA THIS AFTERNOON. THERE ARE AFTERNOON BUILDUPS OVER THE
MOUNTAINS WHERE THERE WILL CONTINUE TO BE A CHANCE OF AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS FOR THE NEXT FEW DAYS. THE LOW
MARINE STRATUS OVER THE COAST SHOULD PUSH BACK INTO THE INTERIOR
OVERNIGHT WITH ONSHORE FLOW CONTINUING. THE BURN OFF WILL PROBABLY
BE A LITTLE EARLIER ON WEDNESDAY AS LOW LEVEL ONSHORE FLOW WEAKENS
AND HIGHS WILL WARM A FEW DEGREES. THE LOW CLOUDS MAY BE LIMITED TO
THE COAST THURSDAY MORNING. HIGHS THURSDAY WILL BE ABOUT THE SAME AS
WEDNESDAY. THE AIR WILL REMAIN UNSTABLE OVER THE MOUNTAINS FOR A
CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS.

.LONG TERM...A WEAK UPPER LOW MAY DROP DOWN FROM THE NORTHWEST OVER
THE WEEKEND...BUT THE BEST CHANCE OF AFTERNOON AND EVENING TSTMS
SHOULD CONTINUE TO BE OVER THE MOUNTAINS EACH DAY. HIGHS WILL BE
NEAR NORMAL AND AREAS OF MORNING LOW CLOUDS SHOULD CONTINUE TO BURN
OFF FOR SOME SUNSHINE FOR THE AFTERNOON AND EVENING.

&&

.AVIATION...THE TSTMS OVER THE MTNS WILL DISSIPATE BY 0600 UTC. THE
PRESENCE OF A BLOCKING UPPER LEVEL HIGH OVER ALBERTA AND CUT-OFF
LOWS NEARBY WILL KEEP THE FLOW ALOFT OVER THE AREA LIGHT AND
VARIABLE. CONTD LOW LEVEL ONSHORE FLOW.

MEANWHILE...THE STRATUS CONTINUED TO RETREAT TOWARD THE COAST.
THE COAST WILL LIKELY REMAIN SOCKED IN TODAY. LOOK FOR LOW CLOUDS
/CIGS MAINLY AOB 1K FT/ TO SURGE BACK INLAND AFTER 0300 UTC...
REACHING THE SOUTH PUGET SOUND BY 0900 UTC. EXPECT AREAS OF FOG TO
REDUCE VSBYS AOB 1SM AFTER 0600 UTC. THE SFC PRES GRADIENT WILL BE
WEAKER WED MORNING THAN THIS MORNING...SO THERE IS A CHANCE THAT
THE STRATUS WILL NOT BLANKET THE ENTIRE PUGET SOUND REGION WED
MORNING.

KSEA...VFR CONDITIONS ARE ANTICIPATED THRU TONIGHT. THERE IS A
POSSIBILITY THAT VFR CONDITIONS COULD PERSIST THRU WED MORNING.
PRESENT THINKING WAS THAT IF THERE IS STRATUS OVER THE TERMINAL
WED MORNING...IT WILL SCATTER OUT EARLIER THAN TODAY.

&&

.MARINE...
LITTLE CHANGE IN THE OVERALL PATTERN IS ANTICIPATED THROUGH THIS
WEEKEND. LOOK FOR A 1025 MB HIGH OFFSHORE WITH LOWER PRES INLAND
TO RESULT IN ONSHORE FLOW OF VARYING STRENGTH. IT IS POSSIBLE THAT
WESTERLY WINDS COULD REACH GALE FORCE OVER THE CENTRAL STRAIT OF
JUAN DE FUCA FRI EVENING.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT WEDNESDAY FOR CENTRAL U.S.
     WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
     STRAIT OF JUAN DE FUCA.

&&

$$

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