124
FXUS66 KSEW 101031
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
331 AM PDT MON MAR 10 2025
SYNOPSIS
ZONAL FLOW ALOFT WITH WEAK LOW LEVEL ONSHORE FLOW
TODAY. NEXT FRONT APPROACHING THE NORTH COAST TONIGHT WILL STALL
AS A DEEP UPPER LEVEL TROUGH DIGS SOUTH OUT OF THE GULF OF ALASKA.
THE FRONT WILL REMAIN STALLED OFF THE COAST TUESDAY THEN MOVE
INLAND TUESDAY NIGHT INTO WEDNESDAY MORNING. COOL UPPER LEVEL
TROUGH BEHIND THE FRONT MOVING OVER THE AREA THURSDAY. NEXT FRONT
SPLITTING BEFORE IT MOVES INLAND FRIDAY NIGHT. ANOTHER SYSTEM IS
POSSIBLE LATER IN THE WEEKEND.
SHORT TERM /TODAY THROUGH WEDNESDAY/
SATELLITE IMAGERY SHOWS
FRONTAL SYSTEM OFF TO THE SOUTHEAST WITH MOSTLY CLOUDY SKIES OVER
WESTERN WASHINGTON. DOPPLER RADAR ONLY PICKING UP A FEW SHOWERS
AT 3 AM/10Z AND MOST OF THOSE ARE IN THE DYING CONVERGENCE ZONE
OVER SNOHOMISH COUNTY. TEMPERATURES WERE IN THE MID 30S TO LOWER
40S.
NOT MUCH GOING ON TODAY. ZONAL FLOW ALOFT OVER THE AREA WITH WEAK
ONSHORE FLOW IN THE LOWER LEVELS. THIS WILL KEEP SKIES MOSTLY
CLOUDY. SATELLITE IMAGERY HAS NO COLD TOP CUMULUS OFFSHORE. A GOOD
INDICATION THAT SHOWER ACTIVITY WILL BE MINIMAL. CLOUD COVER WILL
PREVENT MUCH WARMING TODAY KEEPING HIGHS IN THE MID 40S TO LOWER
50S.
NEXT FRONTAL SYSTEM MOVING INTO THE BRITISH COLUMBIA COASTLINE
OVERNIGHT WITH THE FRONT EXTENDING BACK TO THE SOUTHWEST OVER THE
COASTAL WATERS. LARGE COLD UPPER LEVEL TROUGH DROPPING DOWN OUT OF
THE GULF OF ALASKA WITH THE TROUGH AXIS NEAR 140W. THE DIGGING
TROUGH WILL STOP THE EASTWARD PROGRESSION OF THE FRONT LEAVING IT
OFFSHORE INTO TUESDAY MORNING. RAIN AHEAD OF THE SYSTEM FROM
ABOUT HOQUIAM TO BELLINGHAM BEGINNING OVERNIGHT. RAINFALL AMOUNTS
WILL BE LIGHT. FOR THE REMAINDER OF THE AREA INCREASING CLOUDS.
LOWS IN THE MID 30S TO LOWER 40S.
UPPER LEVEL TROUGH CONTINUING TO DIG SOUTH TUESDAY KEEPING THE
FRONT STALLED OFFSHORE. BEST CHANCES FOR RAIN WILL CONTINUE TO BE
ALONG THE COAST AND OVER THE NORTHWEST INTERIOR. SLIGHT CHANCE OR
CHANCE OF RAIN ELSEWHERE. HIGHS IN THE MID 40S TO LOWER 50S.
UPPER LEVEL TROUGH PUSHING EAST TUESDAY NIGHT WITH THE TROUGH AXIS
NEAR 130W BY 12Z WEDNESDAY. THIS WILL PUSH THE NOW NORTH SOUTH
ORIENTED FRONT ON TO THE COAST EARLY WEDNESDAY MORNING WITH RAIN
SPREADING INLAND TUESDAY NIGHT. WINDS PICKING UP ALONG THE COAST
AND OVER THE NORTHWEST INTERIOR. LOWS NEAR 40.
FRONT MOVING THROUGH EARLY WEDNESDAY MORNING WITH NUMEROUS POST
FRONTAL SHOWERS OVER THE AREA DURING THE DAY. SNOW LEVELS NEAR
3000 FEET AHEAD OF THE FRONT LOWERING TO 2000-2500 FEET BEHIND THE
FRONT GIVING ALL THE PASSES SOME NEW SNOW. HIGHS REMAINING BELOW
NORMAL, NEAR 50.
LONG TERM /THURSDAY THROUGH SUNDAY/
EXTENDED MODELS IN GOOD
AGREEMENT WITH THE UPPER LEVEL TROUGH MOVING INLAND THURSDAY.
TROUGH AXIS RIGHT OVER WESTERN WASHINGTON THURSDAY AFTERNOON COULD
DESTABILIZE THE AIR MASS ENOUGH TO POP A THUNDERSTORM OR TWO.
TROUGH AXIS MOVING EAST OF THE AREA THURSDAY NIGHT.
NEGATIVELY TILTED FRONT ARRIVING LATER FRIDAY MOVING THROUGH
WESTERN WASHINGTON FRIDAY NIGHT. AIR MASS ON THE COOL SIDE BEHIND
THE TROUGH FRIDAY MORNING WITH SNOW LEVELS AROUND OR JUST A LITTLE
BELOW 1000 FEET. THERE IS A CHANCE FOR A LITTLE SNOW IN THE
CASCADE FOOTHILLS BEFORE THE AIR MASS WARMS A TOUCH WITH SNOW
LEVELS AROUND 1500 FEET IN THE AFTERNOON.
ANOTHER COOL UPPER LEVEL TROUGH SATURDAY KEEPING SHOWERS IN THE
FORECAST. MODELS HAVE BEEN SOMEWHAT INCONSISTENT IN THEIR
SOLUTIONS FOR THE SYSTEM SUNDAY. EARLIER MODEL RUNS HAD IT GOING
INLAND SOUTH OF THE AREA. THE OPERATIONAL RUNS ARE STAYING WITH
THIS IDEA BUT THE ENSEMBLES HAVE THE SYSTEM FURTHER NORTH WITH
NUMEROUS WET SOLUTIONS. MODEL BLEND HAS CATEGORICAL POPS AND WILL
GO WITH THIS FOR THE SUNDAY FORECAST. TEMPERATURES REMAINING
BELOW NORMAL THROUGH THE PERIOD WITH SNOW LEVELS IN THE MOUNTAINS
REMAINING BELOW PASS LEVELS. FELTON
AVIATION
WESTERLY FLOW ALOFT AS A WEAK SHORTWAVE IMPULSE PASSES
THROUGH WESTERN WASHINGTON EARLY THIS MORNING. AT THE SURFACE, A
COLD FRONT HAS LARGELY TRAVERSED THE REGION, LEAVING BEHIND A MIXED
BAG OF CEILINGS. AREAS TO THE NORTH AND WEST HAVE BECOME MOSTLY
CLEAR WITH SOME CIRRUS WELL OVERHEAD BEGINNING TO FILL IN.
MEANWHILE, THE GREATER SEATTLE AREA TERMINALS REMAIN MOSTLY MVFR TO
IFR AS CLOUDS AND LIGHT RAIN/DRIZZLE CONTINUES TO TAPER OFF IN A
WEAK POST-FRONTAL CONVERGENCE ZONE. CEILINGS SHOULD LIFT THROUGHOUT
THE MORNING BACK TO VFR ACROSS THE AREA MORE MID TO UPPER LEVEL
CLOUDS BEGIN TO FILL IN. WINDS, FOR MOST, SHOULD BE JUST STRONG
ENOUGH TO LARGELY LIMIT THE POTENTIAL FOR FOG THIS MORNING, THOUGH
SOME LOCALIZED FOG IN SPOTS MAY BE POSSIBLE EARLY THIS MORNING.
VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGHOUT TODAY WITH
INCREASING MID-LEVEL CLOUD COVER AHEAD OF THE NEXT FRONTAL SYSTEM,
WHICH WILL APPROACH THE COAST AND STALL JUST OFFSHORE LATE TONIGHT
INTO EARLY TUESDAY.
WINDS WILL CONTINUE TO DECREASE GOING INTO THIS MORNING AND REMAIN
LIGHT SOUTHWESTERLY, AROUND 5 KT OR LESS, THROUGH THE DAY TODAY.
KSEA...A BRIEF PERIOD OF IFR TO LIFR CONDITIONS THIS MORNING AS THE
REMAINS OF A WEAK CONVERGENCE ZONE PERSISTS OVER THE TERMINAL EARLY
THIS MORNING. MVFR TO IFR CONDITIONS REMAIN POSSIBLE THROUGH AROUND
18Z THIS MORNING BEFORE LIFTING TO VFR UNDER MID-LEVEL CLOUDS THAT
WILL REMAIN THROUGH THE TAF PERIOD. WINDS SOUTHEASTERLY THIS MORNING
WILL SHIFT SLIGHTLY TO SOUTH/SOUTHWESTERLY THIS AFTERNOON, THROUGH
RAMMING AROUND 5 KT OR LESS.
62
MARINE
BROAD HIGH PRESSURE WILL BRIEFLY BUILD OVER THE COASTAL
WATERS TODAY MAKING FOR RELATIVELY LIGHT WINDS OVER THE COASTAL
WATERS. THE NEXT FRONTAL SYSTEM WILL MOVE IN FROM THE NORTHWEST
TONIGHT INTO EARLY TUESDAY MORNING, WITH A SMALL AREA OF INCREASED
WINDS ALONG THE BOUNDARY. THE STRONGEST WINDS WILL BE FOCUSED ACROSS
THE NORTHERN-MOST AREAS OF THE COASTAL WATERS AS WELL AS THE EAST
STRAIT OF JUAN DE FUCA. THE FRONT WILL STALL ON TUESDAY WITH THE
PARENT LOW PRESSURE ARRIVING TUESDAY NIGHT INTO WEDNESDAY, ALLOWING
WINDS TO INCREASE AS IT MOVES THROUGH THE AREA WITH MORE WIDESPREAD
SMALL CRAFT ADVISORY CONDITIONS ACROSS THE COASTAL WATERS AS WELL AS
ANOTHER THROUGH THE INTERIOR WATERS NORTH OF PUGET SOUND GOING INTO
WEDNESDAY MORNING.
THE PATTERN LOOKS TO CONTINUE TO REMAIN ACTIVE WITH SEVERAL
ADDITIONAL SYSTEMS MOVING THROUGH LATE WEEK INTO THE WEEKEND KEEPING
WINDS AND SEAS ELEVATED.
SEAS 8 TO 10 FT WILL SLOWLY EASE TODAY AND INTO EARLY TUESDAY. THE
NEXT SYSTEM WILL PUSH SEAS BACK TO 10 TO 13 FT TUESDAY NIGHT INTO
WEDNESDAY. SEAS LOOK TO REMAIN AROUND 10 TO 12 FT THROUGH AT LEAST
THE END OF THE WEEK.
62
HYDROLOGY
NO RIVER FLOODING IN THE NEXT 7 DAYS. THE SKOKOMISH
RIVER IS IN THE LOWER END OF ACTIONS STAGE THIS MORNING. THE RIVER
WILL CONTINUE TO BE NEAR ACTION STAGE THROUGH THE WEEK. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 AM TO 5 PM PDT TUESDAY FOR ADMIRALTY
INLET-EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 5 PM PDT TUESDAY
FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT
10 NM.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT EARLY THIS MORNING FOR
COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60
NM-COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10
TO 60 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
SHOALWATER 10 TO 60 NM.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 5 AM PDT TUESDAY
FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO
60 NM.
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