Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 271603
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 AM PDT SAT SEP 27 2014

.SYNOPSIS...WEAK HIGH PRESSURE ALOFT WILL BUILD INTO THE REGION THIS
THE WEEKEND FOR DRY WEATHER. A FRONT WILL BRING SOME RAIN TO THE
AREA MONDAY. A FEW SHOWERS WILL LINGER INTO THE MIDDLE OF THE WEEK
WITH A WEAK UPPER TROUGH OVER THE AREA.

&&

.SHORT TERM...AREAS OF MORNING LOW CLOUDS AND FOG ARE MAINLY ALONG
THE I-5 CORRIDOR...ELSEWHERE IT IS MOSTLY SUNNY. ALL AREAS OUGHT TO
BE MOSTLY SUNNY THIS AFTERNOON AS DRIER NORTHERLY LOW LEVEL FLOW
DEVELOPS. AN UPPER RIDGE WILL BE OVER THE AREA ON SUNDAY FOR ANOTHER
DRY DAY. LIGHT NORTHERLY LOW LEVEL FLOW AND MOSTLY CLEAR SKIES
SHOULD RESULT IN AREAS OF FOG AGAIN SUNDAY MORNING. A FRONTAL SYSTEM
WILL BRING RAIN TO THE AREA ON MONDAY...MOSTLY IN THE AFTERNOON FOR
THE INTERIOR. HIGHS WILL BE NEAR NORMAL TODAY...CLIMB A FEW DEGREES
SUNDAY...THEN COOL MONDAY AS CLOUDS AND RAIN MOVE INTO THE AREA.

.LONG TERM...MOIST ONSHORE FLOW WILL PREVAIL ON TUESDAY FOR A CHANCE
OF SHOWERS. AN UPPER TROUGH WILL MOVE THROUGH THE AREA ON WEDNESDAY
BUT IT LOOKS LIKE MOST OF THE WEATHER WILL PASS TO THE NORTH. MODELS
SHOW AN UPPER RIDGE BUILDING OVER THE AREA ON THURSDAY AND THIS MAY
TURN OUT TO BE A DRY DAY. A WARM FRONT IS FORECAST TO COME OVER THE
TOP OF THE RIDGE ON FRIDAY. WHILE THE MODELS AGREE THAT A BROAD
UPPER RIDGE WILL REMAIN OVER THE AREA ON FRIDAY...THEY DIFFER QUITE
A BIT ON HOW WET IT WILL BE. FOR NOW...GIVEN THE HIGH 500 MILLIBAR
HEIGHTS FORECAST TO BE OVER THE AREA...NEAR 580 DECAMETERS...THE
DRIER GFS SOLUTION LOOKS MORE REASONABLE. SCHNEIDER

&&

.AVIATION...AN UPPER LEVEL LOW IS SPINNING OVER THE GREAT BASIN THIS
MORNING...WHILE A WEAK UPPER LEVEL RIDGE IS NUDGING EAST INTO THE
PAC NW. THE FLOW ALOFT IS WESTERLY. THE AIR MASS IS STABLE WITH
AREAS OF LOW CLOUDS OR FOG OVER THE LOWLANDS...LIFR TO IFR
CONDITIONS THIS MORNING. CLOUD TOPS ARE AROUND 1000 FT ON THE LATEST
PILOT REPORTS. NORTH WINDS WILL INCREASE MIXING AND THE LOW CLOUDS
WILL LIFT AND SCATTER THIS AFTERNOON BY 20Z - VFR CONDITIONS
EXPECTED. LOW CLOUDS AND FOG WILL RETURN OVERNIGHT WITH CLEAR SKIES
AND LIGHT WINDS. LIFR TO IFR CONDITIONS ARE LIKELY IN THE INTERIOR
THROUGH SUN MORNING. 33

KSEA...LOW CLOUDS WILL LIFT AND SCATTER BY 20Z WITH VFR CONDITIONS
EXPECTED. SURFACE WINDS WILL REMAIN LIGHT NORTHERLY. LOW CLOUDS AND
FOG WILL RETURN OVERNIGHT WITH LIFR TO IFR CONDITIONS BY 09-12Z. 33

&&

.MARINE...WEAK SURFACE HIGH PRES OVER WESTERN WA WILL GIVE LIGHT
WINDS ACROSS THE REGION TODAY THROUGH SUN. A WEAK COLD FRONT WILL
CROSS THE AREA ON MONDAY. ONSHORE FLOW WILL INCREASE BEHIND THE
FRONT MON NIGHT WITH SMALL CRAFT ADVISORY WINDS FORECAST THROUGH THE
CENTRAL AND EAST STRAIT OF JUAN DE FUCA. ONSHORE FLOW WILL PREVAIL
THROUGH THE MIDDLE OF NEXT WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.

&&

$$

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