High Wind in Washington, December 20 to 21, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
430 PM PST SAT DEC 20 2008

.SYNOPSIS...A STRONG FRONTAL SYSTEM WILL AFFECT THE AREA THIS
EVENING THROUGH SUNDAY MORNING. THIS STORM SYSTEM WILL BRING
SIGNIFICANT SNOW TO MOST AREAS IN WESTERN WASHINGTON AS WELL AS VERY
STRONG WINDS TO THE CASCADE FOOTHILLS. A COLD UPPER LEVEL LOW
TRAILING THE FRONTAL SYSTEM WILL MAINTAIN THE COLD AIR MASS WITH
MORE SNOW SHOWERS EXPECTED ON MONDAY. ANOTHER WEATHER SYSTEM WILL
AFFECT THE REGION ON WEDNESDAY WITH SNOW CHANGING OVER TO RAIN.

&&

.SHORT TERM...HERE WE GO AGAIN. SNOW STARTING TO INCREASE AND SPREAD
NORTH ACROSS W WA THIS AFTERNOON AS WARM MOIST AIR OVERRIDES THE
COLD LOW LEVEL AIRMASS IN PLACE. SNOW LINE IS UP TO NORTHERN KING
COUNTY AND WILL QUICKLY MOVE NE INTO THE NORTHERN ZONES EARLY THIS
EVENING. MODELS CONTINUE TO SHOW HEAVY ACCUMULATIONS WITH THIS
SYSTEM WITH HIGHEST SNOWFALL AMOUNTS ALONG THE COAST AND HOOD
CANAL...ESPECIALLY NEAR THE OLYMPICS. MOUNTAINS OF COURSE WILL GET
HAMMERED AGAIN WITH 1 TO 2 FEET. NORTHWEST WEATHER AND AVALANCHE
CENTER HAS ALSO ISSUED AN AVALANCHE WARNING FOR SUNDAY. ACROSS THE
SEATTLE METRO...WITH SNOW ALREADY HERE EXPECT SNOW TO PILE UP THIS
EVENING AND OVERNIGHT WITH ALL AREAS SEEING MEASURABLE
AMOUNTS...PERHAPS 3 TO 9 INCHES AFTER ALL IS DONE. MODELS STILL SHOW
LESS AMOUNTS ACROSS THE E PUGET SOUND LOWLANDS DUE TO THE DOWNSLOPE
EASTERLIES...BUT COULD STILL SEE UP TO ONE INCH EARLY THIS EVENING.

AS FOR THE WIND...CHECKING THE LATEST OBS HAVE NOT SEEN ANYTHING
SUBSTANTIAL YET...HOWEVER THE PEAK WILL BE LATE THIS EVENING AND
OVERNIGHT FOR THE EAST PUGET SOUND LOWLANDS. SEATTLE TO YAKIMA PRES
GRADIENT HAS BEEN RAPIDLY RISING AND IS NOW OVER 10 MB. SO FORECAST
REMAINS ON TRACK WITH VERY STRONG WINDS STILL EXPECTED. WE DID GET A
REPORT OF 35 TO 40 WITH GUST 50 NEAR SEKIU. TATOOSH ISLAND IS ALSO
REPORTING 45 GUST 55 KT...SO THE BLIZZARD WARNING STILL LOOKS GOOD
FOR THE WEST STRAIT/N COAST.

SNOW WILL TAPER DOWN A BIT DURING THE MORNING WITH EVEN A MIX OF
SLEET OR FREEZING RAIN POSSIBLE IN THE CENTRAL COAST AND LOWER
CHEHALIS VALLEY. HOWEVER...MODELS KEEP WINDS SOUTHEASTERLY AND DOES
NOT LOOK LIKE WE WILL SEE TOO MUCH WARMING DURING THE DAY. IN FACT
WE COULD GET ANOTHER ROUND OF SNOW SHOWERS IN THE AFTERNOON AND
EVENING AS A SECONDARY BOUNDARY OR SFC TROUGH ROLLS THROUGH. WILL
NEED TO WATCH THIS CAREFULLY AS WE MADE NEED TO EXTEND THE WINTER
WEATHER HEADLINES INTO THE AFTERNOON AND EVENING HOURS. MODELS ALSO
NOW INDICATE THAT THE SURFACE LOW WILL PASS SOUTH OF THE AREA LATE
SUNDAY INTO MONDAY WHICH WILL KEEP A COLD NORTHERLY SURFACE WIND
OVER THE AREA...THUS MORE CHANCES FOR SNOW ALTHOUGH OVERALL AMOUNTS
WILL BE LESS. MAY SEE A BRIEF BREAK IN THE WEATHER TUE AS WEAK RIDGE
MOVES OVER WA...WITH TEMPS REBOUNDING TO LOWER 30S. 33

.LONG TERM...ANOTHER SYSTEM WILL APPROACH W WA ON WED BUT AT THIS
POINT IN TIME IT LOOKS LIKE IT WILL BE MOSTLY IN THE FORM OF RAIN
WITH SOUTHERLY ONSHORE FLOW OVER THE LOWLANDS. THE SURFACE TROUGH
WILL SLIDE SOUTH THROUGH W WA ON CHRISTMAS DAY BUT IT STILL
LOOKS LIKE WE WILL SEE MOSTLY RAIN DURING THE DAY...THEN CHANGING
OVER TO SNOW IN THE EVENING...AS THE LOW PASSES FARTHER SOUTH AND
INTO ORE. BEYOND THU...ACTIVE WEATHER WILL PERSIST AS A SERIES OF
SYSTEMS CONTINUE TO AFFECT THE REGION. 33

&&

.AVIATION...FOR THE MOST PART THE INCOMING FRONTAL SYSTEM IS MOVING
IN AS EXPECTED. AT 2230 MODERATE SNOW IS FALLING ON THE CENTRAL
COAST WHILE LIGHT SNOW EXTENDS SOUTHWEST OF A LINE FROM
KCLM-KPAE-KSMP. EXPECT SNOW TO BECOME INCREASINGLY HEAVY AS THE
SYSTEM MOVES ONSHORE OVER QUITE COLD AIR IN PLACE. HEAVIEST
ACCUMULATIONS WILL BE WEST OF PUGET SOUND...IN THE CHEHALIS
GAP...AND IN THE SOUTHWEST INTERIOR OVERNIGHT. THERE IS STILL A RISK
THAT PRECIPITATION WILL CHANGE TO FREEZING RAIN AROUND KHQM BEFORE
GOING TO ALL RAIN IN THE MORNING...AND WILL CHANCE TO SLEET OR
FREEZING RAIN W OF KSHN AND KOLM SOUTHWARD 08Z-15Z TIME FRAME. SINCE
IT WILL BE HARD TO TIME PRECIPITATION RATES...WILL GENERALLY BE
HITTING MOST CENTRAL PUGET SOUND TAFS WITH 1/2SM SN FZFG FOR THE
DURATION OF THE EVENT. USERS SHOULD BE AWARE THAT IT COULD BE
LIGHTER OR HEAVIER AT TIMES.

WIND HAS ALSO BEEN A CONCERN. WHILE CROSS CASCADE PRESSURE GRADIENTS
ARE RAPIDLY INCREASING WITH CROSS CASCADE GRADIENTS NOW OVER 10 MB.
EXPECT WIND IN EAST PUGET SOUND LOWLANDS TOWARD THE CASCADES
INCREASING TO E 30-40 KT GUSTING TO 50-60KT. SOME LOW LEVEL WIND
SHEAR MAY OCCUR WEST OF THE BAND OF EASTERLY WINDS AS IT SHOOTS OVER
COLD AIR NEAR THE SURFACE IN THE PUGET SOUND REGION. HIGHEST CHANCE
FOR LOW LEVEL WIND SHEAR IS AT KBFI AND KSEA.

THE FRONT MOVES ACROSS THE AREA BETWEEN 15Z AND 18Z SUN. AFTER SOME
BREAK IN PRECIPITATION...SNOW OR MIXED RAIN AND SNOW SHOWERS IN THE
INTERIOR AND RAIN SHOWERS ON THE COAST MORNING TO MID
AFTERNOON...MODELS BRING ANOTHER ORGANIZED SHOWER BAND EAST THRU THE
AREA 22Z SUN - 06Z MON. MOST INTERIOR TERMINALS WILL SEE
PRECIPITATION WITH THIS BAND IN THE FORM OF SNOW SHOWERS AND
COMPUTER GUIDANCE INDICATES ACCUMULATIONS OF 2-4 INCHES LIKELY
DURING THE EVENING HOURS.

KSEA...ACCUMULATING SNOWFALL THRU 15Z. EXPECT TOTAL ACCUMULATIONS
3-5 INCHES BY 15Z WITH POSSIBILITY OF 6-8 INCHES DEPENDING ON
STRENGTH OF EASTERLY FLOW. STATISTICAL GUIDANCE CONTINUES TO SHOW
POTENTIAL FOR GREATER THAN 8 INCHES. LOW LEVEL WIND SHEAR WITH WIND
020 AT 10045KT AT TIMES AS EASTERLY FLOW DEVELOPS THIS EVENING AND
MOVES OVER THE TOP OF THE SURFACE LAYER. CONDITIONS IMPROVE ABOUT
15Z WITH PRECIPITATION TAPERING OFF TO SCT -SHSN. TEMPERATURES
LIKELY TO REMAIN COLD ENOUGH AT SEA THAT PCPN REMAINS AS SN THRU 30
HRS. ALBRECHT

&&

.MARINE...SEE FORECASTS FOR DETAILS...STORM WARNING COASTAL WATERS
AND WEST ENTRANCE TO THE STRAIT. GALES ELSEWHERE EXCEPT PUGET SOUND.
WINDS WILL TAPER OFF AS THE FRONT MOVES ACROSS THE AREA AND WEAKENS
SUN MORNING.

A WEAKER FRONT WILL MOVE THRU THE AREA SUN EVENING AS WEAK LOW PRES
MOVES SE INTO NW OREGON. A WEAK TROUGH WILL MOVE THRU THE AREA LATE
TUE WHILE A STRONGER SYSTEM DROPS SE ACROSS THE AREA THU. ALBRECHT

&&

.AVALANCHE...INCREASING STRONG WINDS, MODERATE TO HEAVY SNOW AND A
SLIGHT WARMING TREND ARE EXPECTED TO BUILD NEW UNSTABLE LAYERS
SATURDAY NIGHT AND SUNDAY MORNING. THESE LAYERS ARE LIKELY TO BE
POORLY SUPPORTED BY EXISTING UNDERLYING SNOW. AN AVALANCHE WARNING
IS IN EFFECT SUNDAY. PLEASE SEE WWW.NWAC.US FOR DETAILS. FERBER

ADDITIONAL SYSTEMS MON THRU WED APPEAR WEAKER WITH LOWS SLIDING SE
THROUGH THE COASTAL WATERS AND GIVING OFFSHORE PRES GRADIENTS IN THE
INLAND WATERS. ALBRECHT

&&

WA....SEW WATCHES/WARNINGS/ADVISORIES...

WA...HIGH WIND WARNING IN EFFECT FOR THE EAST PUGET SOUND LOWLANDS
     THROUGH SUNDAY AFTERNOON.

     BLIZZARD WARNING IN EFFECT FOR THE CASCADES THIS EVENING
     THROUGH SUNDAY AFTERNOON AND FOR THE OLYMPICS...WESTERN
      STRAIT OF JUAN DE FUCA AND NORTH COAST LATE.

     WINTER STORM WARNING IN EFFECT FOR THE REMAINING AREA EXCEPT
     THE PUGET SOUND LOWLANDS AND EASTERN STRAIT OF JUAN DE FUCA.

PZ...STORM WARNING COAST AND WEST ENTRANCE TO THE STRAIT.

     GALE WARNING CENTRAL STRAIT...EAST ENTRANCE TO THE STRAIT...
     ADMIRALTY INLET...AND NORTHERN INLAND WATERS.
     SMALL CRAFT ADVISORY PUGET SOUND AND HOOD CANAL.
     SMALL CRAFT ADVISORY GRAYS HARBOR FOR ROUGH BAR CONDITIONS.

WEATHER.GOV/SEATTLE

FOR THE ENHANCED AFD PLEASE VISIT

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
232 PM PST SAT DEC 20 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0232 PM     NON-TSTM WND GST 3 WNW SEKIU             48.28N 124.37W
12/20/2008  M51 MPH          CLALLAM            WA   TRAINED SPOTTER

            SUSTAINED SOUTHEAST WINDS OF 38 MPH. CURRENTLY MODERATE
            SNOW WITH 1/2 MILE VISIBILITY.

&&

GRUB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
411 PM PST SAT DEC 20 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0410 PM     HIGH SUST WINDS  5 WNW SEKIU             48.29N 124.41W
12/20/2008  M40 MPH          PZZ130             WA   TRAINED SPOTTER

            SUSTAINED EAST WINDS 35 TO 40 MPH. GUST TO 52 MPH.
            VISIBILITY LESS THAN A QUARTER OF A MILE WITH HEAVY SNOW.
            2 FOOT SNOW DRIFTS BY THE HOUSE.

&&

GRUB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
419 PM PST SAT DEC 20 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0418 PM     SNOW             1 SW PE ELL             46.57N 123.31W
12/20/2008  M3.0 INCH        LEWIS              WA   TRAINED SPOTTER

            SNOWFALL IN 5 HOURS. CURRENTLY 1/2 MILE IN SNOW AND FOG.

&&

GRUB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
449 PM PST SAT DEC 20 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0447 PM     SNOW             3 ESE NORTH BEND        47.47N 121.74W
12/20/2008  E2.0 INCH        KING               WA   TRAINED SPOTTER

            SOUTHEAST WINDS 35 MPH GUSTING TO 45 AND SNOWING.
            VISIBILITY WAS ONE QUARTER OF A MILE.

&&

WWW.WEATHER.GOV

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE SEATTLE WA
634 PM PST SAT DEC 20 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0232 PM     NON-TSTM WND GST 3 WNW SEKIU             48.28N 124.37W
12/20/2008  M51.00 MPH       CLALLAM            WA   TRAINED SPOTTER

            SUSTAINED SOUTHEAST WINDS OF 38 MPH. CURRENTLY MODERATE
            SNOW WITH 1/2 MILE VISIBILITY.

0410 PM     HIGH SUST WINDS  7 W CLALLAM BAY         48.25N 124.41W
12/20/2008  M40.00 MPH       CLALLAM            WA   TRAINED SPOTTER

            SUSTAINED EAST WINDS 35 TO 40 MPH. GUST TO 52 MPH.
            VISIBILITY LESS THAN A QUARTER OF A MILE WITH HEAVY SNOW.
            2 FOOT SNOW DRIFTS BY THE HOUSE.

0418 PM     SNOW             1 SW PE ELL             46.57N 123.31W
12/20/2008  M3.0 INCH        LEWIS              WA   TRAINED SPOTTER

            SNOWFALL IN 5 HOURS. CURRENTLY 1/2 MILE IN SNOW AND FOG.

0447 PM     SNOW             3 ESE NORTH BEND        47.47N 121.74W
12/20/2008  E2.0 INCH        KING               WA   TRAINED SPOTTER

            SOUTHEAST WINDS 35 MPH GUSTING TO 45 AND SNOWING.
            VISIBILITY WAS ONE QUARTER OF A MILE.

0511 PM     SNOW             12 SW TUMWATER          46.88N 123.10W
12/20/2008  M2.5 INCH        THURSTON           WA   TRAINED SPOTTER

            NEW SNOWFALL. STILL SNOWING. VISIBILITY CURRENTLY ABOUT
            ONE AND A HALF MILES.

&&

WWW.WEATHER.GOV