FXUS66 KSEW 050535
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 PM PST SAT FEB 4 2012

.SYNOPSIS...AN UPPER RIDGE WILL KEEP THE WEATHER DRY THROUGH
TUESDAY. OFFSHORE FLOW WILL PRODUCE LOCALLY GUSTY WINDS NEAR THE
MOUNTAINS THROUGH MONDAY...WHILE WIND PROTECTED AREAS WILL
EXPERIENCE STAGNANT CONDITIONS AND PATCHY MORNING FOG. RAIN IS
POSSIBLE STARTING LATE TUESDAY OR WEDNESDAY AS THE FIRST IN A SERIES
OF WEAK FRONTS MOVES INLAND.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS UPPER LEVEL RIDGE OVER WESTERN
WASHINGTON WITH A WEAKENING FRONT OFFSHORE. PARENT LOW ASSOCIATED
WITH THE FRONT...NEAR 47N/135W...MOVING NORTH NORTHWEST. THIS WILL
MAKE IS HARD FOR THE FRONT TO MAKE MUCH EASTWARD PROGRESS WITHOUT
SPLITTING APART. MODEL SOLUTIONS FOR SUNDAY CONTINUE TO KEEP THE
FRONT OFFSHORE LEAVING WESTERN WASHINGTON DRY AND GIVEN THE CURRENT
SATELLITE IMAGERY SEE NO REASON TO DEVIATE FROM THIS IDEA. IN THE
LOWER LEVELS OFFSHORE FLOW CONTINUES WITH ALL OF THE OFFSHORE
GRADIENTS SLOWLY WEAKENING TONIGHT. THIS TREND WILL CONTINUE INTO
SUNDAY AND COMBINED WITH SOME CIRRUS IN THE AFTERNOON WILL RESULT IN
HIGH TEMPERATURES SLIGHTLY COOLER ON SUNDAY VERSUS TODAYS READINGS
BUT STILL WELL ABOVE NORMAL WITH MANY PLACES INTO THE 50S. CURRENT
MOS GUIDANCE FOR SEATTLE IS 51 DEGREES BUT MOS HAS BEEN RUNNING COOL
THE LAST COUPLE OF DAYS AND WILL STAY WITH THE CURRENT 54 DEGREE MAX
FORECAST. WITH THE OFFSHORE FLOW INTACT THIS EVENING INTO SUNDAY
MORNING EXPECT THE SAME SCENARIO AS THE LAST TWO MORNINGS WITH A
WIDE VARIETY OF LOW TEMPERATURES RANGING FROM NEAR 40 IN THE WIND
EXPOSED AREAS TO THE 20S IN THE WIND SHELTERED AREAS LIKE THE
SOUTHWEST INTERIOR.

LITTLE CHANGE IN THE LOWER LEVELS OF THE AIR MASS THROUGH
AT LEAST MONDAY MORNING WITH THE INVERSIONS CONTINUING. THIS WILL
KEEP THE AIR STAGNATION ADVISORY GOING FOR THE SOUTHWEST
INTERIOR...TACOMA AND HOOD CANAL AREAS.

00Z MODEL RUNS STARTING TO BACK AWAY FORM THE POSSIBILITY OF RAIN ON
TUESDAY NIGHT WITH THE UPPER LEVEL RIDGE REMAINING OVER WESTERN
WASHINGTON AND THE NEXT FRONT SPLITTING AND BECOMING NEGATIVELY
TILTED WITH AN UPPER LEVEL LOW DEVELOPING OFF THE CALIFORNIA COAST.
IF THIS TREND CONTINUES LOOK FOR THE POPS TO BE REMOVED FROM THE
TUESDAY NIGHT FORECAST. CURRENT FORECAST HAS THE TRENDS COVERED. NO
UPDATE THIS EVENING.

.CLIMATE...SEATTLE-TACOMA AIRPORT HAD A MAX OF 60 DEGREES TODAY.
THIS IS THE 85TH TIME THE MAX TEMPERATURE HAS REACHED 60 DEGREES OR
MORE ON A DAY IN FEBRUARY SINCE 1945 WHEN THE RECORDS STARTED AT THE
AIRPORT. THE RECORD FOR THE MOST 60 DEGREE PLUS DAYS IN FEBRUARY IS
9 DAYS SET IN 1963. THE RECORD FOR CONSECUTIVE DAYS WITH HIGHS 60
PLUS IN FEBRUARY IS ALSO 9 DAYS...FEBRUARY 4TH THROUGH THE
12TH...1963. FELTON

.LONG TERM...PREVIOUS DISCUSSION FOLLOWS...THE UPPER RIDGE WILL
REMAIN OVER THE AREA WEDNESDAY AND THURSDAY BUT WEAKEN...ALLOWING
WEAKENING WEATHER SYSTEMS TO REACH THE AREA AND BRING A CHANCE OF
RAIN. THE RIDGE IS EXPECTED TO BREAK DOWN AND SHIFT INLAND AROUND
FRIDAY...POSSIBLE ALLOWING STRONGER AND WETTER FRONTAL SYSTEMS TO
MOVE ONSHORE. MODELS ARE NOT CURRENTLY IN GOOD AGREEMENT WITH THE
DETAILS. FOR NOW HAVE MAINTAINED A NEAR CLIMO POP FORECAST.
SCHNEIDER

&&

.HYDROLOGY...NO FLOODING IS EXPECTED IN THE FORECAST AREA DURING THE
NEXT 7 DAYS. SCHNEIDER

&&

.AVIATION...HIGH PRES OVER THE REGION ALONG WITH LOW LEVEL OFFSHORE
FLOW WILL RESULT IN DRY AND STABLE CONDITIONS. THE VALLEYS...SAN
JUANS AND SOUTH SOUND WILL SEE PATCHY FG OVERNIGHT WHERE THE WINDS
ARE CALM. OTHERWISE EXPECT VFR CONDITIONS THROUGH SUN WITH JUST
FEW-SCT CIRRUS ALOFT. 33

KSEA...VFR CONDITIONS TONIGHT AND SUN. E WINDS 10-15 KT EASING BY
09Z...THEN BECOMING NE.

&&

.MARINE...OFFSHORE FLOW WILL CONTINUE ACROSS WESTERN WA THROUGH
EARLY NEXT WEEK. EASTERLY FLOW WILL STRENGTHEN TONIGHT AS A WEAK
FRONT CROSSES THE COASTAL WATERS. ANOTHER FRONT WILL WEAKEN OFFSHORE
ON MONDAY...HOWEVER MAY SEE EASTERLY GALES THROUGH THE WEST ENTRANCE
OF JUAN DE FUCA. CURRENT FORECAST IS ON TRACK. 33

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...AIR STAGNATION ADVISORY IN EFFECT FOR TACOMA AND
VICINITY...HOOD CANAL AREA...SOUTHWEST INTERIOR...AND LOWER
CHEHALIS VALLEY.

PZ...SMALL CRAFT ADVISORY COASTAL WATERS AND ENTRANCES TO THE STRAIT
OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

$$

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