Winter Storm Watch 7, NWS Seattle, WA

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SEATTLE WA
957 PM PST MON FEB 27 2012

CORRECTED TYPO IN THE SHORT TERM SEGMENT.

.SYNOPSIS...THE NEXT PACIFIC STORM WILL BRING RAIN AND MOUNTAIN SNOW
TO THE AREA ON TUESDAY. A LITTLE SNOW IS POSSIBLE ON THE LOWLANDS
WITH THIS SYSTEM. AN UNSEASONABLY COOL AIR MASS WILL REMAIN OVER THE
REGION FOR A CHANCE OF RAIN OR SNOW SHOWERS THROUGH ABOUT THURSDAY
MORNING. MILDER BUT CONTINUED WET WEATHER IS LIKELY LATER THIS WEEK.

&&

.SHORT TERM..
AN UPPER LOW OVER THE ERN PAC WILL CONTINUE TO MOVE E. EXPECT PRECIP
TO DEVELOP ON THE COAST LATE TUE MORNING AND THEN SLOWLY OVERSPREAD
THE INTERIOR IN THE AFTERNOON. THE NAM WAS A LITTLE FASTER IN
BRINGING THE PRECIP EWD THAN THE GFS. THE GFS ALSO HAD A FARTHER SWD
TRACK OF THE UPPER LOW THAN THE NAM. THE NAM SOLUTION WOULD RESULT
IN STRONGER WIND SPEEDS OVER THE CWA...ESPECIALLY OVER PARTS OF THE
NW INTERIOR. CURRENTLY...A WIND ADVISORY IS IN EFFECT FOR THE COAST
AND NW INTERIOR...WHICH IS FINE CONSIDERING THE DIFFERENCES IN THE
MODELS DETAILS.

BOTH THE NAM AND GFS THICKNESS VALUES INDICATED THAT THE PRECIP
COULD FALL AS A RAIN/SNOW MIX OR SNOW OVER MUCH OF THE LOWLANDS TUE
NIGHT...ESPECIALLY OVER THE HOOD CANAL AREA. THE HOOD CANAL AREA
WILL NEED TO BE WATCHED AS AMOUNTS COULD END UP IN THE ADVISORY OR
LOW END WARNING CRITERIA RANGE. EXPECT THE STEADY PRECIP TO TAPER
OFF TO SHOWERS LATE TUE NIGHT BEHIND THE OCCLUDED FRONT.

THE AIR MASS WILL REMAIN COOL THROUGH THU UNDER CYCLONIC FLOW ALOFT
FOR A CONTINUED THREAT OF LOWLAND SNOW...ESPECIALLY WHERE THE PUGET
SOUND CONVERGENCE ZONE /PSCZ/ DEVELOPS. EXPECT AN UPPER RIDGE TO
BEGIN BUILDING IN FROM THE W DURING THE DAY THU.

.LONG TERM FROM THE PREV DISCUSSION...
THE PATTERN REMAINS PROGRESSIVE INTO THE WEEKEND. HAVE KEPT MOSTLY
CHANCE POPS FOR NOW. A STRONG LOOKING SYSTEM ARRIVES SUNDAY OR
MONDAY AND HAVE MADE RAIN LIKELY THEN. TEMPERATURES WILL BE CLOSER
TO CLIMATOLOGY BUT PERHAPS STILL A DEGREE OR TWO BELOW
AVERAGE...WITH HIGHS NEAR 50 AND LOWS NEAR 40. BURKE

&&

.HYDROLOGY...
FLOODING IS NOT EXPECTED THROUGH EARLY NEXT WEEK.

&&

.AVIATION...AN UPPER LEVEL TROUGH WILL MOVE OVER THE EASTERN PACIFIC
TONIGHT AND TUESDAY WITH INCREASING SOUTHERLY FLOW ALOFT. A FRONTAL
SYSTEM WILL MOVE THROUGH THE COASTAL WATERS TUESDAY AND OVER THE
INTERIOR TUESDAY AFTERNOON AND EVENING. AIR MASS DRY AND
STABLE...BECOMING MOIST ON TUESDAY.

KSEA...HIGH CLOUDS TONIGHT AND TUESDAY MORNING WITH LIGHT NORTH WIND
BECOMING LIGHT SOUTH. INCREASING LOW AND MID CLOUDS AND SOUTH WINDS
TUESDAY AFTERNOON AND EVENING WITH RAIN DEVELOPING LATE IN THE
AFTERNOON AS A FRONTAL SYSTEM MOVES ONSHORE. SHOWERS COULD MIX WITH
SNOW AFTER MIDNIGHT TUESDAY AS COLDER AIR MOVES IN BEHIND THE FRONT
BUT NO ACCUMULATIONS ARE EXPECTED AT THE TERMINAL. SCHNEIDER

&&

.MARINE...A VIGOROUS FRONTAL SYSTEM WILL BRING GALE FORCE SOUTHERLY
WINDS TO MOST WATERS TUESDAY. A SURFACE LOW TRACKING WEST TO EAST
THROUGH THE COASTAL WATERS WILL CONTINUE SMALL CRAFT SOUTHERLY WINDS
MOST WATERS INTO WEDNESDAY. WEAKER ONSHORE FLOW WILL PREVAIL
THURSDAY WITH A MODEST FRONTAL SYSTEM MOVING THROUGH THE WATERS
FRIDAY OR FRIDAY NIGHT. SCHNEIDER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WIND ADVISORY FROM 7 AM TO 10 PM PST TUESDAY FOR THE COAST
     AND NORTHWEST INTERIOR.

PZ...GALE WARNINGS ARE IN EFFECT FOR ALL WATERS EXCEPT THE CENTRAL
     STRAIT OF JUAN DE FUCA AND THE PUGET SOUND/HOOD CANAL.

     SMALL CRAFT ADVISORY FROM 7 AM TUESDAY TO 4 AM PST WEDNESDAY
     FOR THE CENTRAL STRAIT OF JUAN DE FUCA AND THE PUGET SOUND/
     HOOD CANAL.

&&

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