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000
FXUS66 KSEW 060039 AAA
AFDSEW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SEATTLE WA
438 PM PM PST THU DEC 5 2013

.SYNOPSIS...A WEAK WEATHER SYSTEM WILL CLIP THE AREA TONIGHT WITH A
FEW FLURRIES POSSIBLE. COLD AND DRY WEATHER WILL CONTINUE FRIDAY
THROUGH EARLY NEXT WEEK. TEMPERATURES MAY BEGIN TO MODERATE ACROSS
THE REGION NEXT TUESDAY AND WEDNESDAY AS THE LOW LEVEL FLOW FLIPS
BACK TO ONSHORE.

&&

.SHORT TERM...QUICK UPDATE TO THE FORECAST TO ISSUE A WINTER WEATHER
ADVISORY FOR THE NORTH AND CENTRAL COAST. SPOTTER REPORTS OF 1 TO 3
INCHES OF SNOW ARE COMING IN...HIGHEST AT NEAH BAY SO FAR. CAMS SHOW
A LIGHT DUSTING ALONG 101. LIGHT SNOW WILL TAPER DOWN OVER THE NORTH
COAST TONIGHT...WITH LIGHT SNOW ENDING OVER THE CENTRAL COAST EARLY
FRI MORNING. 33


PREVIOUS DISCUSSION FROM 330 PM...A HIGH AMPLITUDE RIDGE OFFSHORE
WILL MAINTAIN NORTH FLOW OVER THE AREA TONIGHT...WHILE DRY LOW LEVEL
OFFSHORE FLOW CONTINUES. A WEAK UPPER LEVEL DISTURBANCE MAY PRODUCE
A FEW FLURRIES ACROSS THE AREA TONIGHT. MODELS SHOW NE PRES
GRADIENTS INCREASING LATE TONIGHT...WITH STRONG NLY WINDS OUT OF THE
FRASER RIVER VALLEY. A WIND ADVISORY IS IN EFFECT FOR THE WESTERN
STRAIT OF JUAN DE FUCA...THE SAN JUANS AND WESTERN WHATCOM FOR WIND
SPEEDS OF 25 TO 35 MPH WITH GUSTS TO 45-50 MPH. TEMPS WILL DROP INTO
THE 20S TONIGHT WITH WIND CHILLS INTO THE TEENS TO SINGLE DIGITS
POSSIBLE...ESPECIALLY ACROSS THE NORTH PART.

THE UPPER LEVEL DISTURBANCE WILL EXIT FRI MORNING WITH SKIES
BECOMING CLEAR AGAIN. WINDY CONDITIONS WILL CONTINUE IN THE NORTH
INTERIOR AND WESTERN STRAIT. TEMPS WILL DROP FURTHER FRI NIGHT WITH
LOWS MAINLY IN THE TEENS. IT WILL BE SUNNY BUT COLD SAT AND SUN WITH
HIGHS NEAR 30 DEGREES. 33

.LONG TERM...THE COLD/DRY WEATHER PATTERN WILL CONTINUE INTO EARLY
NEXT WEEK. WE MAY SEE A LITTLE LIGHT SNOW ON TUE AS A WEAK WARM
FRONT BRUSHES WESTERN WA - ACCUMULATIONS LOOK LIGHT. A SWITCH TO
ONSHORE FLOW WILL BRING WARMER MARINE AIR INLAND ON WED WITH SNOW
LEVELS RISING. HOWEVER WE MAY SEE A PERIOD OF MIXED PRECIPITATION
DURING THIS TRANSITION. A WETTER PAC SYSTEM WILL AFFECT WESTERN WA
WED NIGHT AND THU FOR RAIN AND MOUNTAIN SNOW. BY THEN...LOWLAND
TEMPS WILL MODERATE WITH TEMPS REMAINING ABOVE FREEZING. 33

&&

.CLIMATE...SEATTLE HAS THE POTENTIAL TO HAVE THREE CONSECUTIVE
MORNINGS...SATURDAY...SUNDAY AND MONDAY...WITH A LOW TEMPERATURE
BELOW 20 DEGREES. THE LAST TIME THERE WAS A STRETCH OF AT LEAST 3
DAYS IN A ROW WITH LOWS LESS THAN 20 DEGREES IN SEATTLE WAS DECEMBER
1998 WITH 4 DAYS IN A ROW...DECEMBER 19TH THROUGH THE 22ND. FELTON

&&

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

&&

.AVIATION...MOSTLY DRY NORTHERLY FLOW ALOFT OVER WASHINGTON TONIGHT
WILL BECOME MORE NORTHEASTERLY FRIDAY. A WEAK SYSTEM WILL CONTINUE
MOVING SOUTH OFF THE COAST TONIGHT WITH SOUTHERLY SURFACE FLOW
BECOMING NORTHEASTERLY. THE AIR MASS WILL REMAIN COLD AND MOSTLY
STABLE. HIGH CLOUDS WILL COVER WESTERN WASHINGTON WITH SOME LOW AND
MID LEVEL CLOUDS AND SNOW FLURRIES ALONG THE COAST. CLEARING AFTER
06Z. GENERALLY VFR CONDITIONS ARE EXPECTED EXCEPT FOR LOCAL MVFR
ALONG THE COAST.

KSEA...VFR CIRRUS...CLEARING AFTER 08Z. LIGHT SOUTHEAST WIND WILL
BECOME NORTHEAST BUT REMAIN LESS THAN 10 KT TONIGHT. AFTER 18Z
FRIDAY OR SO NORTHEAST WINDS WILL INCREASE TO 15G25 KT. CHB

&&

.MARINE...AS A WEAK WEATHER SYSTEM OFF THE COAST MOVES SOUTH WINDS
WILL CHANGE FROM SOUTHERLY TO NORTHEASTERLY. NORTHEAST OUTFLOW WINDS
WILL RESUME STARTING LATE TONIGHT. WIND SPEEDS WILL RISE INTO SMALL
CRAFT ADVISORY STRENGTH OVER NORTHERN COASTAL WATERS FIRST TONIGHT
AND SPREAD TO ALL COASTAL ZONES OVERNIGHT. GALE FORCE WINDS ARE
LIKELY IN THE NORTHERN INLAND WATERS AND NEAR THE WEST ENTRANCE LATE
TONIGHT THROUGH SATURDAY MORNING AND A GALE WARNING IS IN EFFECT
OVER THOSE ZONES. BY FRIDAY NIGHT ALL AREAS SHOULD HAVE AT LEAST
SMALL CRAFT ADVISORY STRENGTH WINDS. WINDS WILL EASE BUT STILL
REMAIN MOSTLY NORTHERLY AND OFFSHORE SUNDAY AND MONDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WIND ADVISORY WESTERN WHATCOM...SAN JUANS AND WESTERN STRAIT
     FROM 10 PM TONIGHT UNTIL 4 AM SAT.

PZ...GALE WARNING NORTH INNER COAST...WEST ENTRANCE...AND NORTHERN
     INLAND WATERS EARLY FRIDAY MORNING THROUGH SATURDAY MORNING.
     SMALL CRAFT ADVISORY ALL OTHER WATERS.

&&

$$

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