Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 270429
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 PM PST MON JAN 26 2015

.SYNOPSIS...A WEAK COLD FRONT WILL DISSIPATE OVER WESTERN WASHINGTON
TUESDAY. AN UPPER RIDGE WILL MAINTAIN DRY AND MILD WEATHER WEDNESDAY
THROUGH SATURDAY. THE NEXT FRONT BRINGS A CHANCE OF RAIN BACK INTO
THE AREA SUNDAY AND EARLY NEXT WEEK.

&&

.SHORT TERM...LOW CLOUDS CLEARED OVER THE INTERIOR EARLIER TODAY BUT
HUNG AROUND NEAR THE COAST AND IN THE STRAIT. LOW LEVEL GRADIENTS
ARE WEAK ONSHORE THIS EVENING WHICH SHOULD ALLOW LOW CLOUDS TO
SPREAD PARTIALLY INLAND. A WEAK FRONT OFFSHORE WILL REACH THE COAST
TUESDAY MORNING AND MOVE INLAND DURING THE DAY. THE UPSHOT OF ALL OF
THIS IS INCREASING CLOUDS TONIGHT THEN MOSTLY CLOUDY WITH A LITTLE
RAIN TUESDAY...BEST CHANCES COAST AND MOUNTAINS. THE ADDED CLOUDS
AND STRONGER ONSHORE FLOW WILL RESULT IN HIGHS ABOUT 10 DEGREES
COOLER OVER THE INTERIOR TUESDAY.

SHOWERS WILL DECREASE TO MAINLY OVER THE CASCADES AND POSSIBLY A
PUGET SOUND CONVERGENCE ZONE BEHIND THE FRONT TUESDAY EVENING. AN
UPPER RIDGE WILL REBUILD OVER THE AREA WEDNESDAY AND REMAIN IN
CONTROL THURSDAY. THIS WILL GIVE DRY WEATHER WITH SOME NIGHT AND
MORNING LOW CLOUDS OR FOG AND PARTIAL AFTERNOON SUNSHINE EACH DAY.
SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...AN UPPER LEVEL RIDGE WILL
CONTINUE TO DOMINATE ACROSS THE PAC NW FRI AND SAT FOR MORE DRY AND
STABLE WEATHER. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH HIGHS IN
THE LOW TO MID 50S EACH DAY. A WARM FRONT WILL THEN BRING SOME RAIN
TO THE AREA ON SUN. THIS WARM FRONT MAY STALL OVER THE REGION
THROUGH MONDAY FOR MORE CLOUDY AND RAINY WEATHER. 33

&&

.HYDROLOGY...FLOODING IS NOT EXPECTED FOR THE NEXT 7 DAYS.

&&

.AVIATION...A BROAD UPPER LEVEL RIDGE IS CENTERED OVER IDAHO TONIGHT
WITH SOUTHWEST FLOW ALOFT OVER WESTERN WASHINGTON. A WEAK FRONT JUST
OFFSHORE WILL MOVE INLAND TUESDAY MORNING BEFORE DISSIPATING. MVFR
STRATUS ALONG THE COAST WILL BE PUSHED INLAND AHEAD OF THE FRONT
LATE TONIGHT...WITH MVFR/IFR CONDITIONS DEVELOPING OVER THE INTERIOR
AFTER 12Z. MVFR/LOCAL IFR CONDITIONS ARE EXPECTED OVER THE AREA
THROUGH 18Z...GRADUALLY LIFTING TO MVFR/LOW IFR CIGS. A WEAK PUGET
SOUND CONVERGENCE ZONE MAY FORM AFTER 21Z.

KSEA...GOOD VFR CONDITIONS SHOULD CONTINUE THROUGH 08Z BUT MVFR
STRATUS SPREADING INLAND OVER SW PUGET SOUND SHOULD REACH THE
TERMINAL LATE TONIGHT. THE STRATUS REACHED KSHN AT 0125Z AND SEEMS
HEADED TOWARD KPWT AT 04Z. I HAVE MVFR CIGS DEVELOPING AT KSEA AT
09Z...BUT CONFIDENCE IN THE TIMING IS LOW DUE TO CONFLICTING
GUIDANCE. CIGS BKN-OVC015-025 SHOULD BE PRESENT BY 15Z. SURFACE
WINDS WILL REMAIN S 5-8 KT. KAM

&&

.MARINE...A VERY WEAK FRONT WILL MOVE ACROSS THE COASTAL WATERS
TONIGHT THEN INLAND TUESDAY MORNING. THE SOUTH FLOW AHEAD OF THE
FRONT MAY PRODUCE SOME MARGINAL SCA WINDS OVER THE NORTHERN PART OF
THE COASTAL WATERS TONIGHT. OTHERWISE WINDS ARE EXPECTED TO REMAIN
20 KT OR LESS. A SURFACE RIDGE WILL BUILD OVER THE COASTAL WATERS ON
TUESDAY BEHIND THE FRONT. THE SURFACE RIDGE WILL EXPAND INLAND
TUESDAY AFTERNOON AND EVENING. THE RIDGE WILL EVENTUALLY SET UP OVER
E WA ON WEDNESDAY...ALLOWING A WEAK OFFSHORE FLOW PATTERN TO
DEVELOP...WHICH WILL LAST THROUGH AT LEAST FRIDAY. A COLD FRONT WILL
APPROACH THE REGION ON SATURDAY OR SATURDAY NIGHT. THE 12Z ECMWF IS
A LITTLE FASTER THAN THE 18Z GFS. KAM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR THE FOUR NORTHERN COASTAL ZONES.

&&

$$

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