Heavy Snow in Washington, December 1 to 2, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 AM PST THU DEC 1 2005

.SYNOPSIS...A FRONTAL SYSTEM MOVING INTO OREGON WILL SPREAD LIGHT
RAIN OR SNOW ACROSS WESTERN WASHINGTON THROUGH THIS EVENING. AN
UPPER LEVEL TROUGH WILL MAINTAIN COOL AND SHOWERY WEATHER OVER THE
AREA THROUGH THE WEEKEND.

&&

.SHORT TERM...THIS WILL BE SHORT SINCE THE ZONES STILL NEED
UPDATING. INCOMING SYSTEM IS WEAKER THAN EXPECTED AS MOST MOISTURE
FROM THE SOUTHERN BRANCH PART HAS MOVED EAST OF THE AREA. IR IMAGERY
SHOWS A VORT MAX JUST OFFSHORE HEADING INLAND AND RADAR HAS ECHOES
ALOFT OVER THE AREA. JUST GETTING SOME REPORTS OF LIGHT SNOW
REACHING THE GROUND AROUND PUGET SOUND. WHATS GOOD FOR SNOW IS THAT
THE AIR MASS IS A LITTLE COLDER THAN EXPECTED. WHATS BAD IS THAT
THERE IS LESS MOISTURE AVAILABLE. SO BOTTOM LINE IS THAT A SNOW
ADVISORY IS NOW IN EFFECT FOR THE SW INTERIOR AND GREATER PUGET
SOUND REGION FOR UP TO 2 INCHES OF SNOW. COULD BEGIN AS RAIN OR
RAIN/SNOW MIXED IN SOME AREAS. BOTH 12Z NAM/GFS INDICATED MUCH LESS
PRECIP OVER THE AREA...GENERALLY UP TO TWO TENTHS TOTAL.

STRAIT OF JUAN DE FUCA LOOKS TOO WARM FOR MUCH SNOW AND MAIN
MOISTURE WILL BE S AND EAST. HAVE DROPPED THE WATCH FOR THE NW
INTERIOR...BUT MAY HAVE TO RE-EVALUATE ABOUT A SNOW ADVISORY.

OTHER PROBLEM WAS STRONGER EASTERLY WINDS IN THE ENUMCLAW AREA.
CONSENSUS OF SEVERAL ANEMOMETERS RIGHT AROUND ENUMCLAW POINTED TO
15-30 MPH WITH GUSTS TO 45 MPH. KAM

FROM PREVIOUS SHORT TERM DISCUSSION...ALSO PLAN ON GOING WITH A SNOW
ADV FOR THE NORTH CASCADES AND WARNING FOR THE CENTRAL CASCADES.
THIS IS MORE FOR LATE TONIGHT INTO EARLY SATURDAY AS IT LOOKS LIKE A
SIGNIFICANT SNOW WILL FALL DURING THIS TIME FRAME. THIS WILL ALSO
MATCH UP WELL WITH THE SURROUNDING AREAS.

FOR LATE TONIGHT THROUGH FRIDAY NIGHT OVER THE LOWLANDS...WILL HAVE
A GOOD AMOUNT OF SHOWER ACTIVITY WITH LOW FREEZING LEVELS. SO WILL
HAVE RAIN SHOWERS AND SOME SNOW SHOWERS THAT MAY CAUSE SOME
ACCUMULATIONS AT TIMES. HOWEVER PINPOINTING THE LOCATION OF
ACCUMULATIONS WITH SHOWER ACTIVITY WITH MARGINAL TEMPS NOT POSSIBLE.
WILL WORD AS RAIN AND SNOW SHOWERS FOR NOW.  CERNIGLIA

.LONG TERM...FROM PREVIOUS DISCUSSION...SHOWER THREAT CONTINUES
THROUGH SUNDAY...HOWEVER DIMINISHING THROUGH THE LAST PART OF THE
WEEKEND WITH A SLOWLY WARMING LOW LEVEL AIR MASS.  MODELS CONTINUE
TO INDICATE RIDGING MOVING INTO THE REGION MON AND TUE FOR A PERIOD
OF DRY WEATHER. NO ONE HAS JUMPED ON IT YET (DUE TO NEAR TERM
CONCERNS) AND TO STAY COORDINATED WILL NEED TO KEEP MENTION OF
SHOWERS IN THE FORECAST. WILL DIG INTO THAT FURTHER ON THE NEXT
NIGHT SHIFT.  CERNIGLIA

&&

.AVIATION...VFR CONDS THROUGH 18Z W/ CIGS 5-6K FT OR HIGHER.  LIGHT
RAIN/SNOW MIX WILL INCREASE FROM THE S BEGINNING AT KOLM ARND
18Z...SPREADING INTO KSEA BY ARND 19-20Z.  MVFR CIGS WILL DEVELOP
WITH POCKETS OF IFR POSSIBLE AFT 21Z AS INCREASING PRECIP RATES MAY
TEMPORARILY CHANGE RAIN OVER TO ALL SNOW.  LIGHT ACCUMULATIONS
POSSIBLE MAINLY KPAE SWD...MAINLY A TRACE TO AN INCH OR TWO
OCCURRING LATER THIS AFTERNOON AND EVENING.

KSEA...N/NE WIND 6-11KT THROUGH THE DAY.  LIGHT RAIN/SNOW MIX
BEGINNING ROUGHLY 19Z...CHANGING TO MAINLY LIGHT SNOW AFT ROUGHLY 21
OR 22Z.  ACCUMULATIONS OF A TRACE TO 2 INCHES POSSIBLE...MAINLY
BETWEEN 22Z AND 04Z. MERCER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
    .SNOW ADVISORY THROUGH THIS EVENING FOR THE SOUTHWEST INTERIOR
      AND THE GREATER PUGET SOUND REGION.
    .HEAVY SNOW WARNING CENTRAL CASCADES THROUGH FRIDAY NIGHT.
    .GALE WARNING WEST ENTRANCE STRAIT.
    .SMALL CRAFT ADVISORY COAST...CENTRAL STRAIT...EAST ENTRANCE...
     NORTHERN INLAND WATERS.

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