High Wind Watch 7, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 PM PST SAT DEC 1 2007

.SYNOPSIS...MIXED RAIN AND SNOW SHOWERS WILL CONTINUE
TONIGHT...GRADUALLY TRENDING TO PRIMARILY RAIN AS THE NIGHT
PROGRESSES. A MOIST PACIFIC FRONTAL SYSTEM WILL BRING RAIN ON SUNDAY
WITH ADDITIONAL SNOW IN THE MOUNTAINS. A THIRD VERY WET SYSTEM WILL
BRING HEAVY RAIN AT TIMES SUNDAY NIGHT AND MONDAY...ALONG WITH WINDY
CONDITIONS TO PARTS OF THE AREA. MORE TYPICAL SHOWERY WEATHER WILL
RETURN TUESDAY THROUGH FRIDAY.

&&

.SHORT TERM...PRECIPITATION KEEPS TRYING TO CHANGE TO RAIN AS AS
PRECIPITATION RATES PICK UP...IT GOES BACK TO SNOW. THESE BANDS OF
HEAVIER SHOWERS WILL CONTINUE FOR THE NEXT COUPLE OF HOURS AND
THINGS WILL BEGIN TO TAPER OFF AS THE BEST ENERGY WITH THIS SYSTEM
MOVES NE OF HERE. STRONGER SOUTHERLY WINDS KEEP TRYING TO BREAK
THROUGH AND I BELIEVE THEY WILL EVENTUALLY WIN OUT WHICH WILL HELP
RAISE THE TEMPERATURES OF THE LOWEST LEVELS INTO THE MID 30S. THE
SNOW ADVISORY/WARNING IS SET TO EXPIRE AT 10 PM THIS EVENING AND AT
THE MOMENT THAT STILL LOOKS GOOD. THE FORECAST FOR TODAY PANNED OUT
VERY WELL. THE WARNING FOR THE OLYMPICS IS SET TO EXPIRE AT 10 PM
THIS EVENING BUT I MAY EXTEND THAT INTO EARLY SUNDAY AFTERNOON AS A
FAIR AMOUNT OF SNOW WILL FALL BEFORE THE RAPID RISE IN SNOW LEVEL
OCCURS THERE SUNDAY AFTERNOON.

NEXT CONCERN IS SUNDAY MORNING. LOW LEVEL THICKNESSES REMAIN
DANGEROUSLY LOW SEATTLE NORTHWARD IN THE MORNING AS SURFACE LOW AND
WARM FRONT ARE SOUTH/SOUTHWEST OF HERE AND APPROACHING. STILL THINK
WE COULD HAVE A LITTLE SNOW HERE AND THERE AT THE BEGINNING OF THIS
NEXT SYSTEM BEFORE THE WARM AIR BEGINS TO FLOOD IN ALOFT OVER THE
REGION. THIS WILL NEED TO WATCHED CLOSELY AS IT DEVELOPS AS AT THE
MOMENT WE ONLY HAVE RAIN IN THE FORECAST. THE OTHER AREA OF CONCERN
IS WHATCOM COUNTY NORTH OF THE SAMISH MOUNTAINS WHERE E-NE OUTFLOW
WINDS COULD CONTINUE TO BE AN ISSUE INTO THE AFTERNOON...HOLDING THE
COLD AIR AND POTENTIALLY CONTINUING THE SNOW. WILL ALSO NEED TO BE
WATCHED.

NOW MOVING ONTO MONDAY AND HEAVY RAIN. THE FOLLOWING IS FROM THE
PREVIOUS DISCUSSION AS IS SAYS IT WELL...RAINFALL AMOUNTS FORECAST
FOR THE MOUNTAINS ON MONDAY ARE TRULY BREATHTAKING. 5-10 INCHES IN
SEVERAL BULLSEYES OVER THE OLYMPICS AND CASCADES MEANS FLOODING.
THIS WILL BE ON TOP OF SUNDAY RAIN IN THE OLYMPICS. COULD BE LOOKING
AT SOME VERY HIGH RIVERS FLOWING OFF THE OLYMPICS BY LATE MONDAY. A
FLOOD WATCH IS IN EFFECT FOR EVERYWHERE FOR MONDAY INTO WEDNESDAY.

THE OTHER ISSUE FOR MONDAY IS THE POTENTIAL FOR STRONG WINDS. THIS
STORM SYSTEM HAS VERY IMPRESSIVE WINDS ASSOCIATED WITH IT
(ESPECIALLY JUST OFF THE GROUND THROUGH 8000 FT) DESPITE ASSOCIATED
SURFACE LOW BEING A LONG WAY TO THE WEST. THIS LOOKS LIKE STORM
FORCE WINDS (AT LEAST) ALONG THE COAST AND OVER THE NORTHERN INLAND
WATERS (MOS FOR SIS IS 49 KT). THIS SHOULD ALSO BLEED OVER TO THE
ADJACENT LAND AREAS SO I INTEND TO ISSUE A HIGH WIND WATCH FOR THOSE
AREAS SOON. WITH EXTREME WINDS THROUGH THE MID LEVELS WILL ALSO
INCLUDE THE MOUNTAINS IN THE WATCH. THIS SHOULD BE GOOD FOR 100+ MPH
GUSTS OVER THE RIDGES.   CERNIGLIA

.LONG TERM...AFTER THE MONDAY SYSTEM MOVES ON THROUGH LATER MONDAY
NIGHT...THE NORTHWEST WILL BE LEFT IN A BROAD TROUGH FOR SHOWERS AND
A SLOW COOLING TREND THROUGH THE WEEK. TUESDAY WILL BE WARMER THAN
NORMAL (BUT NOT AS WARM AS MONDAY) WITH AFTERNOON HIGH TEMPERATURES
RETURNING INTO THE 40S AND LOWS INTO THE 30S.  CERNIGLIA

&&

.AVIATION...SLY WIND HAS KICKED IN FROM AROUND THE KING/SNOHOMISH
LINE SWD RESULTING IN MIXED RAIN AND SNOW. NORTH OF THE
KING/SNOHOMISH LINE...MOSTLY SNOW CONTINUING WITH ANOTHER 1 TO 3
INCHES POSSIBLE OVERNIGHT BEFORE CHANGING TO A MIX BY MORNING. IFR
LIKELY AT TIMES NORTH OF SEATTLE...AND PREDOMINATELY MVFR SEATTLE
SWD. CHANGES FOR THE KBLI TAF IS LIKELY AS TEMPS WILL REMAIN COLD
ENOUGH FOR SNOW AT THE ONSET OF PRECIP W/ SUNDAYS SYSTEM.

AT KSEA...TEMPERATURES SUPPORT A MIX OF RAIN AND SNOW THROUGH AT
LEAST 12Z TONIGHT. THE 06Z TAF WILL REFLECT THIS. HEAVIER SHOWERS
MAY RESULT IN BRIEF BURSTS OF SNOW BUT LITTLE IF ANY ACCUMULATION
EXPECTED.  PREDOMINATELY MVFR TONIGHT W/ TEMPO IFR IN HEAVIER
SHOWERS. S WIND 8-12 KT W/ GUSTS TO 20 KT...EASING TO 5-8 KT AFT 09Z
TONIGHT.

SLIGHT UNCERTAINTY EXISTS W/ PRECIP TYPE 12-20Z SUNDAY MORNING AS
ANOTHER SYSTEM MOVES IN. HOWEVER...THE LIKELIHOOD OF A CHANGE BACK
TO SNOW IS PROBABLY LESS THAN 20 PERCENT.  RAIN WILL REMAIN IN THE
TAF.

DTM

&&

.MARINE...SLY WINDS ARE RESULTING IN SCA WINDS MOST WATERS TONIGHT.
WINDS WILL EASE A BIT LATER TONIGHT.

THE NEXT SYSTEM WILL BRING STRONG SE WINDS TO THE COASTAL
WATERS...POSSIBLY GALE FORCE TO THE CENTRAL WASHINGTON
COAST...MAINLY SUNDAY AFTERNOON. A 990 MB SURFACE LOW WILL TRACK
INTO THE CENTRAL OR N WA COAST BY LATE SUNDAY AFTERNOON...WITH
STRONGEST WINDS SOUTH OF THE LOW.

LATE SUNDAY NIGHT AND MONDAY...A VERY POWERFUL STORM WILL TRACK
TOWARD CENTRAL BC...RESULTING IN STRONG SELY PRESSURE GRADIENTS OVER
THE WA/OREGON WATERS. HURRICANE FORCE WINDS WINDS ARE EXPECTED OVER
THE OREGON WATERS...W/ HIGH END STORM FORCE WINDS OVER THE
WASHINGTON COASTAL WATERS.  HURRICANE FORCE GUSTS POSSIBLE IN THE
WASHINGTON WATERS. EXTREME WIND WAVES/SWELL COMBINED POSSIBLY
BUILDING AS HIGH AS 40 FT.

DTM

&&

.AVALANCHE...WITH AN ALREADY UNSTABLE SNOWPACK STRUCTURE WELL
ESTABLISHED THROUGH MULTIPLE BURIED AND NEAR SURFACE WEAK
LAYERS...THE WEATHER FOR THE NEXT 24-36 HOURS APPEARS LIKELY TO
BRING A DRAMATIC INCREASE IN THE AVALANCHE DANGER. PLENTY OF NEW
GRADUALLY DENSER SNOW SLATED TO ARRIVE THROUGH EARLY SUNDAY SHOULD
BEGIN THE DANGER EVOLUTION. THEN WE LOAD THAT SNOW AND THE
UNDERLYING WEAKNESSES WITH LOTS OF HIGHER DENSITY SNOW OR RAIN
SUNDAY AND SUNDAY NIGHT...AS GRADUALLY RISING FREEZING LEVELS AND
INCREASINGLY STRONG WINDS DEVELOP. THE END RESULT SHOULD BE
INCREASINGLY UNSTABLE SNOW AND A HIGH TO EXTREME DANGER BY SUNDAY
NIGHT. HOPE THAT THE JOYS AND THE RECENTLY MORE STABLE APPEARING
SNOW DO NOT LURE FOLKS INTO THINKING THAT ALL IS OKAY WITH OUR
SNOWPACK. IT IS NOT, AND THE STRESSES ADDED TO THE SNOWPACK OVER THE
NEXT DAY OR TWO SHOULD MAKE THAT PRETTY CLEAR. BEST FOR BACH COUNTRY
TRAVELERS TO USE INCREASING CAUTION LATER TODAY...WITH BACK COUNTRY
TRAVEL IN AVALANCHE TERRAIN NOT RECOMMENDED ON SUNDAY. BEST TO AVOID
ANY BACK COUNTRY TRAVEL AT ALL LATER SUNDAY INTO MONDAY. SEE NWAC.US
FOR DETAILS. MOORE

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
.WINTER STORM WARNING CASCADES AND OLYMPICS.
.HEAVY SNOW WARNING HOOD CANAL AREA.
.SNOW ADVISORY FOR REST OF THE LOWLANDS.
.FLOOD WATCH MOST OF WESTERN WASHINGTON.
.GALE WARNING COAST AND W ENTRANCE.
.SMALL CRAFT ADVISORY ALL REMAINING WATERS.
.SMALL CRAFT ADVISORY GRAYS HARBOR BAR FOR ROUGH BAR CONDITIONS.

WEATHER.GOV/SEATTLE

PRELIMINARY LOCAL STORM REPORT CORRECTED
NATIONAL WEATHER SERVICE SEATTLE WA
532 PM PST SAT DEC 01 2007

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

0531 PM     SNOW             3 NE MILL CREEK         47.89N 122.16W
12/01/2007  M3.0 INCH        SNOHOMISH          WA   NWS EMPLOYEE

&&

CERNIGLIA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
535 PM PST SAT DEC 01 2007

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

0535 PM     SNOW             5 ENE BELLEVUE          47.62N 122.04W
12/01/2007  M2.5 INCH        KING               WA   TRAINED SPOTTER

            NO LONGER SNOWING.

&&

MCDONNAL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
618 PM PST SAT DEC 01 2007

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

0617 PM     HEAVY SNOW       3 SW BRINNON            47.65N 122.94W
12/01/2007  M7.0 INCH        JEFFERSON          WA   TRAINED SPOTTER

            STILL SNOWING AND 31 DEGREES.

&&

MCDONNAL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
636 PM PST SAT DEC 01 2007

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

0635 PM     HEAVY SNOW       2 N POTLATCH            47.40N 123.14W
12/01/2007  M7.0 INCH        MASON              WA   TRAINED SPOTTER

&&

MCDONNAL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
726 PM PST SAT DEC 01 2007

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

0531 PM     SNOW             2 S EVERETT             47.93N 122.20W
12/01/2007  M3.5 INCH        SNOHOMISH          WA   PUBLIC

            0.25 MELTED

0531 PM     SNOW             3 ENE REDMOND           47.69N 122.06W
12/01/2007  M4.0 INCH        KING               WA   TRAINED SPOTTER

            30 DEGREES WITH MODERATE SNOW.

&&

CERNIGLIA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
755 PM PST SAT DEC 01 2007

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

0745 PM     SNOW             1 SE EVERETT            47.95N 122.18W
12/01/2007  M4.8 INCH        SNOHOMISH          WA   NWS EMPLOYEE

0754 PM     SNOW             NORTH BEND              47.50N 121.79W
12/01/2007  M2.0 INCH        KING               WA   PUBLIC

&&

CERNIGLIA