Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 142315
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 PM PST SUN DEC 14 2014

.SYNOPSIS...AN UPPER RIDGE OVER WESTERN WASHINGTON TODAY WILL SHIFT
EAST TONIGHT. A SERIES OF WEAK SPLITTING SYSTEMS WILL MOVE ACROSS
THE AREA FOR MOST OF THE WORK WEEK.

&&

.SHORT TERM...SKIES ARE MOSTLY CLEAR ACROSS WESTERN WA THIS
AFTERNOON THANKS TO HIGH PRES ALOFT AND OFFSHORE WINDS. TEMPS ARE IN
THE UPPER 40S TO MID 50S ACROSS THE REGION. SKIES WILL REMAIN MOSTLY
CLEAR THIS EVENING WITH CLOUDS MOVING IN FROM THE SOUTHWEST
OVERNIGHT. WILL LIKELY SEE PATCHY FOG DEVELOP OVER THE SOUTHWEST
INTERIOR. EXPECT LOWS IN THE 30S.

A WEAK SPLITTING FRONT WILL BRING LIGHT RAIN MAINLY TO THE COAST ON
MONDAY. A TROUGH AXIS WILL THEN LIFT NORTH THROUGH WESTERN WA MONDAY
NIGHT INTO TUESDAY...ALTHOUGH RAINFALL TOTALS LOOK LIGHT. THERE IS A
CHANCE OF RAIN ACROSS THE REGION TUESDAY AFTERNOON THROUGH WEDNESDAY
WITH AN UPPER LEVEL TROUGH OVER THE PAC NW. BUT AGAIN THE RAINFALL
TOTALS LOOK VERY LIGHT AND SPOTTY. SO OVERALL JUST ISOLATED TO
SCATTERED ACTIVITY OVER THE NEXT FEW DAYS WITH LITTLE PRECIP IF
ANYTHING. TEMPS ARE CLOSE TO NORMALS. 33

.LONG TERM...THE GFS IS TRYING TO BUILD A WEAK UPPER LEVEL RIDGE
OVER THE PAC NW ON THURSDAY FOR A DRY PERIOD OF WEATHER. HOWEVER
LEFT LOW-END CHANCE POPS IN THE FORECAST AS THE ECMWF STILL BRUSHES
WESTERN WA WITH A LITTLE MOISTURE. A COLD FRONT WILL THEN MOVE
INLAND ON FRIDAY FOR SOME RAIN. THE GFS IS THE WEAKER SOLUTION AS IT
SHOWS THIS FRONT SPLITTING AS IT MOVES INLAND. THE ECMWF IS WETTER
AND A BLEND OF THE ECMWF AND GFS WAS USED FOR THIS PERIOD. A COOL
UPPER TROUGH WILL CROSS THE AREA FRIDAY NIGHT INTO SATURDAY FOR A
FEW SHOWERS. A WETTER PAC SYSTEM WILL MOVE INTO SOUTHERN B.C. ON
SUNDAY...POSSIBLY CLIPPING WESTERN WA SUN NIGHT OR MON AS IT SHIFTS
SOUTH. 33

&&

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

&&

.AVIATION...AN UPPER RIDGE OVER WRN WA WILL MOVE INTO THE NRN GREAT
BASIN OVERNIGHT. EXPECT AN UPPER TROF OVER THE NERN PACIFIC TO
APPROACH THE COAST DURING THE DAY MON. ELY FLOW ALOFT WILL BECOME
SLY OVERNIGHT. CONTD MODERATELY STRONG LOW LEVEL OFFSHORE FLOW.

VFR CONDITIONS PREVAILED ACROSS THE AREA THIS AFTERNOON AND SHOULD
PERSIST OVERNIGHT. THERE MIGHT BE PATCHY CIGS AND VSBYS BLO 500 FT
AND 1SM...RESPECTIVELY...AFTER 0600 UTC.

KSEA...VFR CONDITIONS THRU MON MORNING. WINDS WILL REMAIN ELY AT
8-13 KNOTS...WITH OCNL GUSTS NEAR 20 KNOTS.

&&

.MARINE...
MODERATELY STRONG EASTERLY FLOW WILL CONTINUE THROUGH MON DUE TO LOW
PRES OFFSHORE AND HIGHER PRES INLAND. THE EASTERLY FLOW WILL WEAKEN
MON NIGHT AND TUE. LIGHT OFFSHORE FLOW WILL PREVAIL ON WED. A COLD
FRONT IS EXPECTED TO APPROACH THE AREA THU NIGHT AND THEN MOVE
ACROSS THE REGION ON FRI.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...GALE WARNING IN EFFECT TIL 6 AM MON FOR THE NEARSHORE WATERS
     FROM CAPE FLATTERY TO JAMES ISLAND AND THE WEST ENTRANCE TO
     STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORIES ARE IN EFFECT FOR MUCH OF THE COASTAL
     WATERS AND THE CENTRAL/EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

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