629
FXUS66 KSEW 200252
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
752 PM PDT SUN OCT 19 2025
SYNOPSIS
UNSETTLED AND COOL CONDITIONS WILL CONTINUE OVER
REGION THIS AFTERNOON. UPPER LEVEL RIDGING LOOKS TO BUILD TONIGHT
THROUGH TUESDAY WITH DRYING CONDITIONS OVER THE AREA. A FRONTAL
SYSTEM LOOKS TO ARRIVE LATE WEDNESDAY, WITH ANOTHER WET AND
POTENTIALLY STRONGER SYSTEM ARRIVING LATER IN THE WEEK THROUGH THE
WEEKEND WHICH COULD POTENTIALLY BRING MODERATE TO HEAVY RAIN AT
TIMES, BREEZY WINDS, AND MOUNTAIN SNOW.
SHORT TERM /TONIGHT THROUGH WEDNESDAY/
HEAVY SNOW HAS ENDED IN
THE NORTH CASCADES AND THE WINTER WEATHER ADVISORY HAS BEEN
CANCELLED. SNOW LEVELS ARE AROUND 4500-5000' WITH UP TO 2 INCHES
OVER THE HIGHER PEAKS AND PASSES. VERY ACTIVE CONVERGENCE ZONE
TODAY BUT THUNDER CHANCES HAVE DECREASED WITH THE UPPER TROUGH
MOVING EAST OF THE CREST. 33
PREVIOUS DISCUSSION...AN UPPER LEVEL RIDGE BEGINS TO BUILD
OVERNIGHT INTO MONDAY, WITH CONDITIONS STARTING TO DRY OUT OVER
THE AREA. HIGH TEMPERATURES ON MONDAY WILL TREND IN THE UPPER 50S,
WITH SOME LOCATIONS POTENTIALLY REACHING THE LOW 60S.
CONDITIONS WILL CONTINUE TO BE DRY INTO TUESDAY WITH SUNSHINE AT
TIMES, MAKING TUESDAY LIKELY THE WARMEST DAY IN THE WEEK, WITH
TEMPERATURES IN THE LOWER 60S FOR MUCH OF THE AREA. ENSEMBLES
HAVE BEEN IN AGREEMENT WITH A A WEAK SYSTEM MOVING IN WEDNESDAY
WITH SOME LIGHT SHOWERS SPREADING ACROSS THE REGION. HIGH
TEMPERATURES WILL STAY IN THE MID TO UPPER 50S.
LONG TERM /THURSDAY THROUGH SUNDAY/
THE PATTERN BECOMES MORE
ACTIVE IN THE LONG TERM AS A STRONGER SYSTEM MOVES OVER WESTERN
WASHINGTON ON THURSDAY INTO FRIDAY. THERE ARE STILL SOME STRENGTH
INCONSISTENCIES BUT IT DOES LOOK LIKE THIS SYSTEM WILL BRING
MODERATE TO HEAVY RAIN AT TIMES, WITH WIDESPREAD RAIN ACROSS THE
REGION. MOST OF THE PRECIPITATION WILL LIKELY BE OROGRAPHICALLY
LIFTED AND FALL IN THE OLYMPICS AND THE CASCADES. ADDITIONALLY, WINDS
LOOK TO BECOME BREEZY OVER MUCH OF THE AREA, ALONG WITH MOUNTAIN
SNOW. RAIN LOOKS TO CONTINUE THROUGH MUCH OF THE WEEKEND AS A
COOL UPPER LEVEL TROUGH REMAINS PARKED OVER THE PACIFIC NORTHWEST,
KEEPING THE PATTERN UNSETTLED AND RAINY.
MAZURKIEWICZ
AVIATION
NORTHWESTERLY FLOW TONIGHT INTO MONDAY MORNING BEFORE
BECOMING MORE WEST-NORTHWESTERLY. SURFACE WINDS REMAIN SOUTHERLY FOR
MOST TERMINALS WITH THE EXCEPTIONS OF HQM AND CLM WHERE WESTERLY
WINDS ARE PRESENT, AND PAE SEEING NORTHERLY WINDS THANKS TO THE
WESTERLIES DOWN THE STRAIT. SPEEDS HAVE EASED A LITTLE AHEAD OF
SCHEDULE WITH THE MAJORITY OF TERMINALS SEEING SPEEDS RANGING 4-8
KTS. THE EXCEPTIONS ARE THE SAME TERMINALS LISTED ABOVE AND OLM IS
STILL SEEING SOME GUSTS AS WELL. THESE TERMINALS WILL ALSO SEE
SPEEDS EASE AT OR A LITTLE AFTER 03Z, WITH SPEEDS 8-12 KTS LIKELY IN
THE 03-05Z TIME FRAME, THEN JOINING THE REMAINING TERMINALS IN THE 4-
8 KTS RANGE OVERNIGHT.
GENERALLY VFR CONDITIONS IN PLACE OVER W WA THIS EVENING WITH SOME
ISOLATED LOCATIONS IN THE SAN JUANS AND ALONG THE COAST REPORTING
MVFR CONDITIONS. WITH PLENTY OF LOW LEVEL MOISTURE IN THE WAKE OF
THE EXITING SYSTEM, MVFR TO IFR CIGS EXPECTED TO DEVELOP OVERNIGHT.
CIGS EXPECTED TO RECOVER TO WIDESPREAD VFR CONDITIONS AFTER 18-20Z,
ALTHOUGH MODELS DISAGREE TO THE EXTENT OF IMPROVEMENT. MOST FEASIBLE
SCENARIO IS CIGS BREAK UP SOME, BUT MID-LEVEL CLOUDS LIKELY STILL
REMAIN BKN FOR THE REMAINDER OF THE TAF PERIOD.
KSEA...VFR CONDITIONS IN PLACE AND THAT WILL LIKELY REMAIN THE CASE
FOR THIS EVENING AND EARLY TONIGHT. AS MENTIONED ABOVE, ABUNDANT LOW
LEVEL MOISTURE WILL BRING CIGS DOWN OVERNIGHT TO MVFR CONDITIONS BY
12Z AND REMAIN THERE UNTIL LIFTING AROUND 18-20Z. WHILE ANY CLEARING
MAY BE A LITTLE TOO OPTIMISTIC, CIGS WILL RECOVER TO AROUND 7000 TO
10000 FT AND REMAIN THERE FOR THE REST OF THE TAF PERIOD. SURFACE
WINDS HAVE EASED A LITTLE EARLY, BUT IN SPITE OF THE PSCZ COMING
CLOSE TO THE TERMINAL, WINDS HAVE REMAINED SOUTHWESTERLY AND WILL
LIKELY SHIFT A LITTLE MORE SOUTHERLY TONIGHT. GUSTS HAVE LARGELY
WRAPPED UP, SO OVERNIGHT WIND SPEEDS GENERALLY EXPECTED TO BE 6-10
KTS.
18
MARINE
WITH INCREASING ONSHORE FLOW ACROSS THE WATERS BEHIND THE
PASSING FRONT THAT IS NOW WELL EAST, CONTINUING TO SEE STRONG WEST
WINDS DEVELOP THROUGH THE STRAIT OF JUAN DE FUCA AS WELL AS THE
COASTAL WATERS. EXPECT PERSISTENT WESTERLIES IN THE STRAIT TO LINGER
INTO TONIGHT. THUS, THE GALE WARNING FOR THE CENTRAL STRAIT WILL
REMAIN IN PLACE THROUGH 10 PM. MEANWHILE, SEAS HAVE PEAKED OVER THE
COASTAL WATERS AT 18-23 FT, AND WILL GRADUALLY SUBSIDE INTO MONDAY.
CONDITIONS WILL REMAIN QUITE ROUGH ON THE GRAYS HARBOR BAR
OVERNIGHT, ESPECIALLY AROUND THE EBBS THIS EVENING AND EARLY MONDAY
MORNING.
HIGH PRESSURE BUILDS OVER THE WATERS WITH WINDS MONDAY AND TUESDAY
NOT NEARLY AS STRONG. HOWEVER, WILL NEED TO WATCH FOR BUILDING WAVES
AGAIN TUESDAY AS A WEAK SYSTEM PASSES TO THE NORTH. WHILE CURRENT
NWPS OUTPUT SUGGESTS WAVES AROUND 15-17 FEET, THERE'S SOME SIGNAL
FOR SOME ENHANCEMENT AS WAVES GENERATED NEAR THE GULF OF ALASKA AND
OFF NORTHERN VANCOUVER ISLAND MAKE THEIR WAY INTO THE LOCAL WATERS.
MORE SIGNIFICANTLY, A STRONGER FRONTAL SYSTEM MOVING TOWARD THE
LOCAL AREA THURSDAY INTO FRIDAY MAY BRING ANOTHER ROUND OF 20+ FT
SEAS, WITH THE ECMWF ENSEMBLE GUIDANCE SUGGESTING NON-TRIVIAL
CHANCES OF SEAS EVEN APPROACHING 25 FT OVER THE COASTAL WATER. WHILE
THERE'S LOW CERTAINTY WITH RESPECT TO THE PRECISE TRACK OF THAT
STRONGER SYSTEM, IT'S WORTH NOTING THAT EVEN A SYSTEM THAT DOESN'T
TRACK IMMEDIATELY THROUGH THE LOCAL AREA CAN STILL SPREAD LARGE
WAVES ACROSS THE NORTHEASTERN PACIFIC AND INTO THE COASTAL WATERS.
EVEN WITH THE CURRENT GUIDANCE, THERE'S A HIGH POTENTIAL OF AT LEAST
GALE GUSTS ACROSS MUCH OF THE WATERS (>75% CHANCE) AND AT LEAST A 40-
50% CHANCE OF LOCALIZED STORM FORCE GUSTS THURSDAY NIGHT AND FRIDAY.
CULLEN/18
HYDROLOGY
A WETTER SYSTEM WILL ARRIVE LATER THURSDAY INTO
FRIDAY. THIS SYSTEM COULD BE TAPPING INTO SOME SUB TROPICAL
MOISTURE BRINGING UP THE POSSIBILITY OF HYDROLOGICALLY SIGNIFICANT
RAINFALL OVER THE OLYMPICS THURSDAY NIGHT INTO FRIDAY. CURRENT
FORECAST HAS 2 TO 4 INCHES OF PRECIPITATION OVER THE OLYMPICS
THURSDAY NIGHT INTO FRIDAY. SNOW LEVELS NOT EXCESSIVELY HIGH, 6000
TO 7000 FEET, KEEPING SOME OF THE WATER IN THE OLYMPICS IN THE
FORM OF SNOW INSTEAD OF RUNOFF. THERE IS STILL PLENTY OF TIME FOR
THIS SOLUTION TO CHANGE. THE FIRST SKOKOMISH RIVER FLOOD OF THE
SEASON IS STILL A POSSIBILITY.
FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 6 PM PDT MONDAY FOR COASTAL WATERS
FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-COASTAL
WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO 60 NM-
COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE OUT 10
NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER
10 TO 60 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
SHOALWATER OUT 10 NM-GRAYS HARBOR BAR.
SMALL CRAFT ADVISORY UNTIL 6 AM PDT MONDAY FOR EAST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA-NORTHERN INLAND WATERS
INCLUDING THE SAN JUAN ISLANDS-WEST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 10 PM PDT THIS EVENING FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 6 AM PDT MONDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA.
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