Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 201144
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
344 AM PST THU NOV 20 2014

.SYNOPSIS...WEAK LOW PRESSURE ALOFT WILL PREVAIL OVER THE REGION
TODAY FOR SCATTERED SHOWERS. THE AREA WILL BE BETWEEN SYSTEMS
TONIGHT. A STRONGER PACIFIC STORM WILL IMPACT THE REGION ON FRIDAY
FOR LOCALLY HEAVY RAIN AND GUSTY WINDS...ALONG WITH THE POTENTIAL
FOR DECENT SNOWFALL IN THE MOUNTAINS. THE WEATHER PATTERN WILL
REMAIN WET AND UNSETTLED THIS WEEKEND.

&&

.SHORT TERM...
A WEAK COLD OR OCCLUDED FRONT WAS MOVING ACROSS THE CWA AT THIS
TIME AND WILL EXIT THE AREA BY SUNRISE. IT LOOKS LIKE THE THREAT
OF FREEZING RAIN HAS ENDED IN THE PASSES. THE PRECIP WILL MOST
LIKELY FALL AS SNOW OR A RAIN/SNOW MIX...DEPENDING ON THE
ELEVATION. NOT MUCH PRECIP WAS OCCURRING BEHIND THE FRONT PER
DOPPLER RADAR DATA. THUS...LOOK FOR SCATTERED SHOWERS TO PREVAIL
ACROSS THE AREA TODAY UNDER WEAK CYCLONIC FLOW ALOFT.

WESTERN WA WILL BE BETWEEN SYSTEMS TONIGHT BUT THERE MAY BE A FEW
LINGERING SHOWERS OVER THE AREA...ESPECIALLY OVER THE NORTH COAST
AND NORTH CASCADES.

A STRONGER PACIFIC STORM WILL IMPACT THE REGION ON FRI FOR LOCALLY
HEAVY RAIN AND GUSTY WINDS IN THE FAVORED AREAS /COAST AND
NORTH INTERIOR/. A WIND ADVISORY WILL LIKELY BE NEEDED FOR THESE
AREAS FOR LATE FRI MORNING THROUGH AT LEAST FRI AFTERNOON.

IT LOOKS LIKE THE CASCADES ABOVE 4000 FEET WILL RECEIVE WINTER
WEATHER ADVISORY CRITERIA SNOWFALL AMOUNTS OR AMOUNTS IN THE 6 TO
11 INCH RANGE FRI NIGHT...ALTHOUGH IT IS POSSIBLE THAT MOUNT BAKER
COULD RECEIVE ABOUT A FOOT OF SNOW.

THE COLD FRONT WILL SWEEP ACROSS THE CWA FRI NIGHT. EXPECT THE
UPPER TROF TO MOVE ACROSS THE REGION EARLY SATURDAY. THE AIR MASS
WILL REMAIN UNSTABLE ENOUGH FOR PLENTY OF SHOWERS ON SATURDAY. IN
ADDITION...A PUGET SOUND CONVERGENCE ZONE WILL LIKELY DEVELOP IN
ITS FAVORED LOCATION...NEAR THE KING/SNOHOMISH COUNTY BORDER...IN
THE WAKE OF THE COLD FRONT.

.LONG TERM...
ANOTHER LOW PRESSURE SYSTEM WILL MOVE ACROSS THE PACIFIC NORTHWEST
ON SUNDAY...THUS POPS WERE BUMPED UP TO CATEGORICAL. AN UPPER
RIDGE IS EXPECTED TO PREVAIL OVER THE REGION ON MON. IF THIS TREND
CONTINUES...LATER SHIFTS COULD REMOVE POPS FROM THE FORECAST
ALTOGETHER. BEYOND MON...THE MEDIUM RANGE SOLUTIONS DIVERGED...
THEREFORE CONFIDENCE IN THE FORECAST FOR TUE AND WED WERE NOT
HIGH. LEFT THE INHERITED FORECAST INTACT FOR THIS REASON.

&&

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

&&

.AVIATION...A COLD FRONT NOW OVER WESTERN WASHINGTON WILL EXIT TO
THE NORTHEAST THIS MORNING. SOUTHERLY FLOW ALOFT WILL BECOME
WESTERLY. AT THE SURFACE MODERATE SOUTHEAST GRADIENTS WILL EASE IN
THE AFTERNOON. AFTER THE FRONT PASSES THE AIR MASS WILL BE MOIST AND
SLIGHTLY UNSTABLE WITH SCATTERED SHOWERS.

CEILINGS BEHIND THE FRONT WILL GENERALLY BE 2-4K FT WITH A FEW IFR
CEILINGS AT TIMES. SOME IMPROVEMENT IN THE AFTERNOON AND EVENING IS
LIKELY.

KSEA...MVFR CEILINGS LIKELY THIS MORNING WITH SOME IMPROVEMENT IN
THE AFTERNOON. WIND SOUTHEAST 6-10 KT. CHB

&&

.MARINE...MODERATE SOUTHEAST FLOW IN THE WAKE OF A FRONT WILL KEEP
SMALL CRAFT ADVISORY WINDS GOING OVER MOST WATERS THIS MORNING.
WINDS WILL EASE IN THE AFTERNOON.

MODELS BRING A STRONGER FRONT INLAND FRIDAY. SOLID GALES ARE LIKELY
OVER THE COAST FRIDAY AFTERNOON AND EVENING AND THE WARNING IS NOW
POSTED. MODELS SHOW SOME GALE FORCE WINDS OVER THE EAST ENTRANCE AND
NORTHERN INLAND WATERS AND THERE IS NOW A GALE WATCH FOR THOSE AREAS.

WESTERLY FLOW ALOFT OVER THE NORTHEAST PACIFIC SATURDAY THROUGH
MONDAY WILL BRING SEVERAL WEAK SYSTEMS ACROSS THE AREA. POST FRONTAL
WINDS ON SATURDAY COULD HAVE SOME PUNCH BUT FOR NOW HAVE KEPT WINDS
UNDER GALE FORCE. SWELLS IN THE 15-20 FOOT RANGE ARE FORECAST TO
REACH THE COAST SUNDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT TIL 10 AM THIS MORNING FOR ALL
     WATERS EXCEPT THE CENTRAL STRAIT OF JUAN DE FUCA AND THE
     PUGET SOUND/HOOD CANAL.

     SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH BAR TIL 6 AM FRIDAY
     FOR THE GRAYS HARBOR BAR.

     GALE WARNING IN EFFECT FROM 7 AM TO 10 PM FRIDAY FOR THE
     COASTAL WATERS.

     GALE WATCH IN EFFECT FROM FRIDAY MORNING THROUGH FRIDAY
     EVENING FOR EAST ENTRANCE TO THE STRAIT OF JUAN DE FUCA AND
     THE NORTHERN INLAND WATERS.

&&

$$

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