143
FXUS66 KSEW 241633
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
933 AM PDT FRI MAY 24 2013
.SYNOPSIS...AN AREA OF LOW PRESSURE WILL REMAIN OVER THE REGION
THROUGH THIS WEEKEND FOR CONTINUED SOMEWHAT UNSETTLED CONDITIONS.
HOWEVER...THE OVERALL TREND WILL BE TOWARD LESS SHOWERS...MORE
SUNSHINE...AND WARMER DAYTIME TEMPERATURES. MEMORIAL DAY MIGHT END
UP DRY FOR MUCH OF THE AREA.
&&
.SHORT TERM...
SOME AREAS IN THE NORTHERN PART OF THE CWA WERE SEEING SOME SUNSHINE
THIS MORNING. HOWEVER...WITH DAYTIME HEATING...LOOK FOR CUMULUS
CLOUDS TO BUBBLE UP WITHIN THESE CURRENTLY MOSTLY SUNNY AREAS.
THE 0900 UTC RUN OF THE SREF /SHORT RANGE ENSEMBLE FORECAST/
INDICATED INSTABILITY OVER THE NORTH CASCADES THIS AFTERNOON FOR A
SLIM RISK OF A TSTM. HOWEVER...THE STRONGEST LIFT THIS AFTERNOON
APPEARED TO BE OVER THE WESTERN PART OF THE FORECAST AREA...SO
WOULD NOT RULE OUT A FEW TSTMS OVER THIS AREA. WILL GO ON AHEAD
AND UPDATE THE FORECAST TO INCLUDE A MENTION OF AFTERNOON TSTMS
OVER THESE AREAS.
MEANWHILE...AN UPPER LOW WILL REMAIN OVER THE REGION THROUGH
SATURDAY MORNING. THE SHOWER THREAT WILL MAINLY BE DIURNAL IN
CHARACTER OR WITH THE GREATEST PROBABILITY AND COVERAGE DURING
THIS AFTERNOON AND EVENING. THE UPPER LOW WILL MOVE INTO EASTERN
WA SATURDAY AFTERNOON...WITH THE BEST THREAT OF SHOWERS BECOMING
CONFINED TO THE MOUNTAINS.
IT NOW APPEARS THAT SATURDAY NIGHT WILL BE MOSTLY DRY UNDER WEAK
CYCLONIC FLOW ALOFT. A WEAK UPPER TROF WILL REMAIN OVER THE REGION
ON SUNDAY FOR A CHANCE OF MAINLY AFTERNOON SHOWERS. IT LOOKS LIKE
THE BEST CHANCE OF SHOWERS WILL BE OVER THE SOUTHERN PART OF THE
FORECAST AREA.
.LONG TERM FROM THE PREV DISCUSSION...
COOL ONSHORE FLOW WILL PREVAIL THROUGH THE REST OF THE WEEK FOR
MOSTLY CLOUDY SKIES AND TEMPS NEAR NORMAL. MODELS SHOWED A LONG
WAVE TROUGH OVER THE PAC NW FOR ADDITIONAL SHOWERS ACROSS THE
REGION...AT LEAST THROUGH MIDWEEK. WEAK RIDGING MAY BRING DRIER
WEATHER BY THU OR FRI. 33
&&
.AVIATION...AN UPPER LEVEL TROUGH OVER WA WILL SLOWLY MIGRATE EWD
LATER TODAY AND TONIGHT. LIGHT VARIABLE FLOW BECOMING SWLY THIS
AFTERNOON. MOIST AND SLIGHTLY UNSTABLE. SCATTERED SHOWERS...WITH
BEST CHANCES FROM HQM SOUTH...DECREASING OVER ALL WESTERN WA BY
TONIGHT. LESS THAN A 10 PERCENT CHANCE OF ISOLATED THUNDERSTORMS
THIS AFTERNOON/EARLY EVENING.
KSEA...VARIABLE WIND TO 5 KT BECOMING S 5 TO 8 KT BY 16Z. MAINLY LOW
END VFR/HIGH END MVFR...DROPPING TO MVFR DURING SHOWERS. VFR CIGS
EXPECTED AFTER 18Z.
&&
.MARINE...LIGHTER GRADIENTS AND WINDS OVER THE WA WATERS TODAY AS
LOW PRESSURE MOVES INLAND. WEAK ONSHORE FLOW LATER TODAY INCREASES A
BIT TONIGHT THROUGH THE WEEKEND. INHERITED FORECAST PUT LOW END
SMALL CRAFT WINDS IN THE CENTRAL AND EASTERN STRAIT STARTING LATE
THIS AFTERNOON AND INTO THE OVERNIGHT HOURS...SO WILL SEND ADVISORY
WITH UPCOMING MORNING FORECAST.
THE NEXT ORGANIZED FRONT REACHES THE WATERS ON MONDAY WITH SMALL
CRAFT WINDS PROBABLE OVER THE COASTAL WATERS AND POSSIBLY SOME OF
THE INTERIOR WATERS.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT FROM 5 PM THIS AFTERNOON TO 2
AM PDT SATURDAY FOR THE CENTRAL AND EASTERN STRAIT OF JUAN DE
FUCA.
&&
$$
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