Winter Storm Watch 8, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 AM PST THU MAR 8 2012

.SYNOPSIS...HIGH PRESSURE WILL GIVE ANOTHER DRY AND WARMER DAY
TODAY. RAIN WILL RETURN FRIDAY OR FRIDAY NIGHT AS A COLD FRONT MOVES
ACROSS THE AREA. ANOTHER FRONT WILL MOVE ACROSS THE AREA LATER
SATURDAY. A DEEP UPPER LEVEL TROUGH WILL BRING COOL AND WET WEATHER
TO THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK.

&&

.SHORT TERM...AN UPPER LEVEL RIDGE OVER THE AREA TODAY WILL SHIFT
INLAND TONIGHT. LOW LEVEL FLOW WILL BECOME OFFSHORE TODAY AND THE
AIR MASS WILL WARM...ALLOWING HIGHS TO WARM SEVERAL DEGREES COMPARED
TO WEDNESDAY.

CLOUDS FROM AN APPROACHING FRONTAL SYSTEM WILL BEGIN TO SPREAD INTO
THE AREA TONIGHT. THIS WILL GIVE MILDER OVERNIGHT LOWS COMPARED WITH
THE LAST TWO NIGHTS AND THERE MIGHT EVEN BE A LITTLE RAIN AFTER
MIDNIGHT AT THE NORTH COAST.

LATEST MODELS HAVE REVERSED TRENDS WITH THE FRIDAY FRONT A BIT
WEAKER AND SLOWER. RAIN AT THE COAST LOOKS CERTAIN BUT IT MIGHT BE A
MOSTLY DRY DAY OVER THE INTERIOR...ESPECIALLY FROM SEATTLE SOUTH.
THE FRONT WILL SLOWLY SHIFT INLAND AND WEAKEN FRIDAY NIGHT...ONLY TO
REPLACED BY ANOTHER FRONT MOVING ONSHORE ON SATURDAY.

IT LOOKS LIKE MOUNT BAKER COULD GET HEAVY SNOW FROM THE FRIDAY
FRONT...BETWEEN ROUGHLY 18Z FRIDAY AND 12Z SATURDAY. THE CENTRAL
CASCADES LOOK LIKE THEY WILL GET LESS SNOW. A WINTER STORM WATCH
WILL BE ISSUED FOR THE NORTH CASCADES TO COVER THIS. SCHNEIDER

.LONG TERM...MODELS START TO SHOW TIMING DIFFERENCES SATURDAY NIGHT
AND SUNDAY. THE GFS IS A BIT FASTER WITH A FRONT MOVING INLAND
SATURDAY NIGHT THEN A COOL AND SHOWERY UPPER LEVEL TROUGH SETTLING
OVER THE REGION SUNDAY AND SUNDAY NIGHT. THE ECMWF HAS THE SAME
GENERAL IDEA BUT IS A BIT SLOWER WITH THESE EVENTS. EITHER WAY...
THIS PERIOD LOOKS WET. BY SUNDAY NIGHT...THE AIR MASS WILL BE COLD
ENOUGH FOR THE HIGHER PARTS OF THE LOWLANDS TO BE FLIRTING WITH SNOW
AGAIN IN SCATTERED SHOWERS.

MONDAY THROUGH WEDNESDAY LOOKS CONTINUED COOL AND WET AS ADDITIONAL
FRONTS MOVE THROUGH BUT MODELS ARE CURRENTLY HAVING A HARD TIME
PINNING DOWN THE SPECIFICS. SCHNEIDER

&&

.HYDROLOGY...A FAIRLY WET FRONTAL SYSTEM IS FORECAST BY THE MODELS
MONDAY OR TUESDAY BUT DETAILS REMAIN UNCERTAIN. MODELS FORECAST A
PERIOD OF 850 MB SOUTHERLY WINDS 50-60 KNOTS INTO THE SOUTHERN
OLYMPICS DURING THIS TIME BUT SNOW LEVELS ARE EXPECTED TO REMAIN
FAIRLY LOW. ALL IN ALL...THIS IS NOT SHAPING UP TO BE A LIKELY FLOOD
PATTERN. FOR NOW...THE BEST CHANCE FOR FLOODING WITH THIS PATTERN
WOULD BE ON THE SKOKOMISH RIVER IN MASON COUNTY. OTHERWISE...THE
THREAT OF FLOODING DURING THE NEXT SEVEN DAYS IS LOW. SCHNEIDER

&&

.AVIATION...AN UPPER RIDGE WILL PREVAIL OVER THE REGION TODAY.
ANTICIPATE INCREASING WLY FLOW ALOFT. THE LOW LEVEL FLOW WILL BE
OFFSHORE. A DRY AIR MASS OVER THE AREA WILL RESULT IN VFR CONDITIONS
TODAY.

KSEA...EXPECT HIGH CLOUDS TO STREAM ACROSS THE AREA TODAY. NLY SFC
FLOW WILL BECOME ELY BY LATE MORNING...AND THEN VARIABLE THIS
AFTERNOON.

&&

.MARINE...A 1032 MB HIGH OVER THE GEORGIA STRAIT WILL MOVE INTO FAR
NORTHEAST WASHINGTON DURING THE DAY TODAY. NORTHERLY FLOW EARLY THIS
MORNING WILL BECOME EASTERLY. THE FLOW WILL BECOME SOUTHERLY TONIGHT
AS A WEAK COLD FRONT APPROACHES. THIS FRONT WILL MOVE ACROSS THE
AREA ON FRI. A STRONGER FRONTAL SYSTEM WILL IMPACT THE AREA ON
SATURDAY.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER STORM WATCH NORTH CASCADES ABOVE 3500 FEET FRIDAY
     AFTERNOON AND FRIDAY NIGHT.
PZ...SMALL CRAFT ADVISORY NORTHERN COASTAL WATERS AND WEST ENTRANCE
     STRAIT OF JUAN DE FUCA.

WWW.WEATHER.GOV/SEATTLE

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