Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 300354
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT SUN MAR 29 2015

.SYNOPSIS...A STATIONARY FRONT WILL BRING RAIN AT TIMES TO NORTHERN
AND COASTAL SECTIONS THROUGH MONDAY. A COLD FRONT WILL SPREAD RAIN
ACROSS THE AREA MONDAY NIGHT. AN UPPER LEVEL TROUGH WILL SETTLE OVER
THE PACIFIC NORTHWEST TUESDAY AND WEDNESDAY PROVIDING COOL SHOWERY
WEATHER. SHOWERS WILL DECREASE THURSDAY...THEN RAIN DEVELOPS FRIDAY
AS THE NEXT TROUGH MOVES OVER THE REGION.

&&

.SHORT TERM...THE STATIONARY FRONT THAT HAS BROUGHT RAIN AT TIMES TO
THE COAST AND NORTHERN INTERIOR FOR THE LAST 24 HOURS OR SO WILL
CONTINUE TO DO SO FOR ANOTHER 24. TOMORROW WILL BE ONE LAST DAY IN
THE WARM SECTOR AND HIGH TEMPERATURES ARE FORECAST TO BE IN THE 60S.
A COLD FRONT WILL FINALLY MOVE THROUGH MONDAY NIGHT...SPREADING RAIN
OVER THE WHOLE AREA.

SHOWERS AND BREEZY CONDITIONS WILL FOLLOW ON TUESDAY. HEIGHTS WILL
FALL SIGNIFICANTLY WITH HIGH TEMPERATURES ONLY REACHING THE LOW TO
MID 50S. THE SNOW LEVEL WILL FALL TO AS LOW AS 3000 FEET. THIS MEANS
THERE WILL BE SNOW IN THE PASSES AND ALSO IN A PUGET SOUND
CONVERGENCE ZONE IN THE MOUNTAINS. A SNOW ADVISORY COULD BE NEEDED.

SHOWERS TAPER WEDNESDAY. A LITTLE WARMING IS LIKELY. BURKE

.LONG TERM...PREVIOUS DISCUSSION...THE GFS/ECMWF ARE COMING INTO
BETTER AGREEMENT SHOWING A SHORT WAVE RIDGE ON THURSDAY...THE
ANOTHER TROUGH ARRIVING FRIDAY. THERE COULD STILL BE SOME WEAK
DIURNAL SHOWER ACTIVITY THURSDAY AND THE GFS DOES KEEP SOME SPOTTY
LIGHT QPF AROUND. LEFT A CHANCE OF SHOWERS IN THE FORECAST FOR NOW
BUT POPS MIGHT NEED TO BE PULLED IF MODELS CONTINUE WITH THE RIDGE
SOLUTION.

A FRONT BRINGS RAIN INTO WESTERN WASHINGTON ON FRIDAY...THEN A
TROUGH MOVES INTO THE REGION OVER THE WEEKEND. IT WILL BE COOL AND
UNSETTLED WITH SHOWERS ACROSS THE AREA. SNOW LEVELS WILL BE LOW AT
AROUND 3000 FEET BUT THE SHOWERY PATTERN IS PROBABLY NOT CONDUCIVE
FOR MUCH SNOW ACCUMULATION. MERCER

&&

.HYDROLOGY...FLOODING IS UNLIKELY OVER THE NEXT 7 DAYS.

&&

.AVIATION...A BROAD FLAT UPPER RIDGE WILL REMAIN OVER THE REGION
TONIGHT...THEN WEAKEN AND MOVE EAST MONDAY AS A COLD FRONT MOVES
INTO THE COASTAL WATERS. WESTERLY FLOW ALOFT TONIGHT WILL BACK TO
SOUTHWEST MONDAY. THE AIR MASS WILL BE GENERALLY STABLE AND MOIST
BELOW 10000 FT.

MOSTLY VFR CONDITIONS ACROSS THE FORECAST AREA THIS EVENING WITH
SCT030-040 BKN050-070 OVC090-120. THERE ARE AREAS -- MAINLY ALONG
THE COAST AND IN THE NORTH INTERIOR -- OF OVC023-030 WITH -RA. ON
THE WHOLE THERE WILL NOT BE MUCH CHANGE THROUGH MONDAY.

KSEA...SOUTH WIND 5-10 KT.   MCDONNAL

&&

.MARINE...A RIDGE OVER WESTERN WASHINGTON WILL WEAKEN EARLY MONDAY
AS A COLD FRONT MOVES INTO THE COASTAL WATERS. THE FRONT WILL MOVE
INLAND MONDAY EVENING...FOLLOWED BY STRONG ONSHORE FLOW MONDAY NIGHT
AND TUESDAY. SMALL CRAFT ADVISORY CONDITIONS WILL PREVAIL FOR MOST
OF THE MARINE ZONES THROUGH THIS PERIOD...AND WESTERLY GALES ARE
POSSIBLE IN THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA LATER
MONDAY NIGHT AND TUESDAY.

ONSHORE FLOW WILL WEAKEN WEDNESDAY AND THURSDAY AS A RIDGE BUILDS
OVER THE REGION. A RELATIVELY WEAK FRONT WILL PROBABLY REACH THE
AREA FRIDAY.   MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY ALL WATERS EXCEPT THE CENTRAL STRAIT.
     SMALL CRAFT ADVISORY GRAYS HARBOR FOR ROUGH BAR.
     GALE WATCH FOR MONDAY NIGHT AND TUESDAY CENTRAL STRAIT AND
       EAST ENTRANCE STRAIT.

&&

$$

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML







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