Wind Advisory 20, NWS Seattle, WA

000 
WWUS76 KSEW 160946
NPWSEW

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE SEATTLE WA
146 AM PST TUE DEC 16 2008


WAZ001-503-515-161100-
/O.CAN.KSEW.WI.Y.0020.000000T0000Z-081216T1200Z/
SAN JUAN COUNTY-WESTERN WHATCOM COUNTY-
WESTERN STRAIT OF JUAN DE FUCA-
146 AM PST TUE DEC 16 2008

...WIND ADVISORY IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN SEATTLE HAS CANCELLED THE WIND
ADVISORY FOR WESTERN WHATCOM COUNTY...THE SAN JUAN ISLANDS...AND
THE WESTERN STRAIT OF JUAN DE FUCA.

WINDS HAVE DIMINISHED BELOW ADVISORY CRITERIA SINCE MIDNIGHT AS
THE NORTHERLY PRESSURE GRADIENT HAS EASED.

&&

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PST MON DEC 15 2008

.SYNOPSIS...MODIFIED ARCTIC AIR WILL CONTINUE TO FLOW INTO WESTERN
WASHINGTON ALL WEEK. WINDY CONDITIONS... ESPECIALLY IN THE NORTH
INTERIOR AND NEAR THE STRAIT OF JUAN DE FUCA WILL ACCOMPANY THE COLD
AIR TONIGHT. A FRONTAL SYSTEM WILL BRING MORE SNOW WEDNESDAY...AND
COLD WEATHER WILL CONTINUE TO GRIP THE REGION ALL WEEK.

&&

.SHORT TERM...TONIGHT WILL BE COLD WITH LOW TEMPERATURES IN THE
TEENS. GRADIENTS HAVE LESSENED A BIT AND ANTICIPATE THIS TREND TO
CONTINUE. THIS MEANS THE HIGH WIND WARNINGS IN THE NORTH INTERIOR
AND OVER THE WESTERN STRAIT WILL EXPIRE AT 3 PM...TO BE REPLACED BY
WIND ADVISORIES FOR SOMEWHAT LESS STRONG WIND. TUESDAY WILL ALSO BE
SUNNY AND COLD...WITH TEMPS PERHAPS A FEW DEGREES HIGHER...BUT STILL
AROUND FREEZING.

NEXT WEATHER SYSTEM IS DUE WEDNESDAY. THERE WILL BE CLOUDS
INCREASING FROM THE NORTH TUESDAY NIGHT...AND A CHANCE OF SNOW IN
THE NORTHERN AREAS THEN. ON WEDNESDAY THERE WILL BE WIDESPREAD
PRECIPITATION OUT OF THIS WEATHER SYSTEM AS A SURFACE LOW MOVES
SOUTH ALONG THE COAST AND AN UPPER LOW SETTLES OVER WESTERN
WASHINGTON.

THE PRECIPITATION WILL BE SNOW...EXCEPT POSSIBLY ON THE COAST WHERE
ONSHORE FLOW COULD MAKE IT RAIN OR MIXED RAIN AND SNOW. THE REAL
QUESTION IS HOW MUCH SNOW. MM5 SHOWS HEAVY SNOW...4 INCHES OR
MORE...IN MANY LOCATIONS...ESPECIALLY THE EAST PUGET SOUND LOWLANDS
AND THE NORTHWEST AND SOUTHWEST INTERIORS. THE STRAIT AREA IS ALSO
LIKELY TO GET DECENT SNOW. SEATTLE METRO AREA AND PERHAPS THE
KITSAP/MASON AREA COULD BE SPARED HEAVY SNOW AS UPPER FLOW IS MOSTLY
WESTERLY AND THERE COULD BE SOME SHADOWING BY THE OLYMPICS. PERHAPS
ONLY AN INCH OR TWO COULD FALL IN THESE AREAS.

SNOW FORECASTING IS NOT SO EXACT THAT WFO SEATTLE IS WILLING TO BET
THE FARM ON THIS IDEA...SO HAVE GONE WITH A WINTER STORM WATCH ALL
ZONES. DETAILS CAN BE WORKED OUT LATER AFTER SOME MORE MODEL RUNS.

HAVE ALSO POSTED THE WINTER STORM WATCH IN THE CASCADES AND OLYMPICS
WHERE WESTERLY FLOW ALOFT SHOULD BE PERFECT FOR HEAVY SNOW.

THE WATCH PERIOD ENDS AT 12Z THURSDAY. BY THIS TIME THE SYSTEM WILL
HAVE MOVED OFF TO THE SOUTHEAST AND ONLY SHOWERS WILL REMAIN. THESE
WILL BE SNOW SHOWERS AND ANOTHER INCH OR TWO SEEM POSSIBLE THURSDAY
AS WELL. BURKE

.LONG TERM...HAVE NOT CHANGED THE MAIN IDEAS...WHICH CALL FOR A DRY
PERIOD ON FRIDAY...AND A WEATHER SYSTEM OVER THE WEEKEND. GFS BRINGS
A PACIFIC SYSTEM IN FROM THE WEST. THIS WOULD PROBABLY MEAN
PRECIPITATION BEGINNING AS SNOW...FALLING HEAVILY FOR AWHILE...THEN
TURNING TO RAIN. HOWEVER...IN COORDINATION WITH ADJACENT OFFICES...
HAVE OPTED FOR THE EURO SOLUTION. THIS KEEPS WESTERN WASHINGTON DRY
ON SATURDAY...AND ONLY BRUSHES US ON SUNDAY WITH A SYSTEM MOVING
INTO OREGON. THIS SOLUTION KEEPS THE AREA COLD AND ANY PRECIPITATION
ON SUNDAY WOULD BE SNOW. WITH THE GFS AND EURO DIFFERING SO MUCH
CONFIDENCE IS NOT HIGH IN EITHER SOLUTION. BURKE

&&

AVIATION...VERY DRY OFFSHORE FLOW CONDITIONS WILL PERSIST THROUGH
TUESDAY. MODERATE NORTHEAST FLOW ALOFT. FOG NOT EXPECTED DUE TO
STABLE AND DRY CONDITIONS.

A WEATHER SYSTEM DROPPING SOUTH ALONG THE BRITISH COLUMBIA COAST
WILL SPREAD MID AND HIGH CLOUDS OVER THE AREA TUESDAY NIGHT. EXPECT
FLURRIES TO DEVELOP TUESDAY NIGHT...INCREASING TO WIDESPREAD LIGHT
SNOW ACROSS THE AREA BY EARLY WEDNESDAY MORNING AND CONTINUING AT
TIMES THROUGH WEDNESDAY NIGHT. IT IS STILL TOO EARLY TO DETERMINE
AMOUNTS. HOWEVER...TEMPERATURES WILL REMAIN AT OR BELOW FREEZING
THROUGH THE PERIOD SO ANY SNOW THAT DOES FALL WILL STICK. CONTINUE
TO MONITOR FORECASTS CLOSELY.

KSEA...CLEAR WITH NE WIND TO 8-14 KT. DRY AIR MASS THROUGH TUESDAY.
DTM

&&

.MARINE...STRONG OFFSHORE FLOW AND NORTHEAST FRASER OUTFLOW WILL
PERSIST THROUGH THIS EVENING...THEN GRADUALLY EASE OFF OVERNIGHT.
KEPT THE GALE GOING FOR THE N INTERIOR...ENTIRE STRAIT...AND NORTH
PORTION OF THE COASTAL WATERS TONIGHT.  THE NORTHERLY WINDS
ELSEWHERE ARE STRONG ENOUGH TO WARRANT A SMALL CRAFT ADVISORY.
EXPECT LIGHTER OFFSHORE WINDS ON TUESDAY.

A LEE SIDE LOW WILL FORM NEAR VANCOUVER ISLAND AND POSSIBLE ACROSS
THE INLAND WATERS WEDNESDAY AFTERNOON...DROPPING SOUTH WEDNESDAY
EVENING. EXPECT ANOTHER BURST OF OUTFLOW WINDS FROM THE
FRASER...POSSIBLY BRINGING NEAR STORM FORCE WINDS NORTHEAST WINDS TO
THE NORTH INTERIOR WEDNESDAY NIGHT. TEMPERATURES WILL ALSO PLUMMET
WITH A HIGHER THREAT OF FREEZING SPRAY INTO THURSDAY MORNING. DTM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER STORM WARNING ALL ZONES LATE TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT.
WIND ADVISORY TONIGHT WESTERN WHATCOM COUNTY...SAN JUAN COUNTY...AND
THE WESTERN STRAIT OF JUAN DE FUCA AREA.
PZ...STORM WARNING NORTHERN INLAND WATERS.
GALE WARNING NORTH COAST WATERS AND STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY CENTRAL COAST...ADMIRALTY INLET...AND PUGET
SOUND AND HOOD CANAL.

WEATHER.GOV/SEATTLE

FOR THE ENHANCED AFD PLEASE VISIT

WWW.WEATHER.GOV/SEATTLE/GAFD/LATESTWEBAFD.HTML (ALL LOWERCASE)