998
FXUS66 KSEW 050328
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
728 PM PST THU DEC 4 2025
SYNOPSIS
A VERY ACTIVE PATTERN IS UNDERWAY THROUGH THE NEXT WEEK WITH A
SERIES OF SYSTEMS BRINGING ROUNDS OF RAIN, HIGHER ELEVATION
SNOW, AND WINDY CONDITIONS THROUGH THE END OF THE WEEK AND THIS
WEEKEND. A MORE SIGNIFICANT ATMOSPHERIC RIVER EVENT IS ON TRACK
TO REACH THE AREA MONDAY AND INTO EARLY NEXT WEEK FOR
WIDESPREAD SIGNIFICANT RAINFALL AND HYDROLOGIC IMPACTS. COASTAL
FLOODING DUE TO HIGHER ASTRONOMICAL TIDES WILL REMAIN MINOR
INTO EARLY NEXT WEEK.
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
THE LATEST FORECAST REMAINS ON TRACK THIS EVENING WITH NO
UPDATES. RAIN CONTINUES TO FALL ACROSS THE AREA THIS EVENING.
THIS WILL TAPER OFF A BIT INTO TONIGHT UNTIL ANOTHER WAVE MOVES
ACROSS THE AREA FRIDAY BRINGING A REINFORCING ROUND OF RAINFALL.
AMOUNTS WILL BE FAIRLY LIGHT ACROSS THE INTERIOR WITH THE
HEAVIEST RAINFALL FOCUSED ALONG THE COAST, THE WESTERN OLYMPICS,
AND MOST NOTABLY, THE CASCADES, WHERE 2-3" WILL BE POSSIBLE
THROUGH SATURDAY AFTERNOON. MORE DETAILS ON THE HYDROLOGIC
IMPLICATIONS BELOW. LOWERING SNOW LEVELS FRIDAY NIGHT INTO
SATURDAY MORNING WILL ALLOW A TRANSITION TO SNOW AT LOCATIONS
DOWN TO 4000 FT. THIS WILL ALLOW FOR A ROUND OF SIGNIFICANT
ACCUMULATING SNOWFALL AT STEVENS PASS, FOR WHICH A WINTER
WEATHER ADVISORY HAS BEEN ISSUED. AMOUNTS OF AROUND 5 TO 10" ARE
CURRENTLY FORECAST. HEAVY SNOWFALL RATES UNDER A CONVERGENCE
ZONE OR IN PERIODS OF HEAVY PRECIPITATION MAY CREATE HAZARDOUS
CONDITIONS. WINDY CONDITIONS MAY LIMIT VISIBILITY AT TIME. ON
THAT NOTE, WINDS WILL INCREASE FRIDAY INTO FRIDAY NIGHT, WITH
GUSTS UP TO AROUND 20 TO 30 MPH. PRECIPITATION AND WINDS WILL
TAPER OFF AREA- WIDE SATURDAY NIGHT.
HIGHS FRIDAY AND SATURDAY IN THE LOW TO MID 50S WITH LOWS IN THE
MID TO UPPER 40S.
TIDES WILL PEAK FRIDAY ALONG THE PACIFIC COAST AND SATURDAY
THROUGH THE INTERIOR WATERS. MINOR COASTAL FLOODING WILL BE
POSSIBLE ALONG THE COAST, STRAIT, AND NORTH INTERIOR WATERS IN
THIS TIME FRAME. COASTAL FLOOD ADVISORIES HAVE BEEN ISSUED AS
APPROPRIATE.
LONG TERM /SUNDAY THROUGH THURSDAY/
THE OVERALL LONG-TERM FORECAST REMAINS ON TRACK WITH ANOTHER
WAVE OF RELATIVELY LIGHTER PRECIPITATION ON SUNDAY BEFORE AN
ATMOSPHERIC RIVER PATTERN BEGINS TO SET UP MONDAY AND PERSIST
THROUGH THE REST OF THE PERIOD. DURING THAT TIME, SIGNIFICANT
RAINFALL IS EXPECTED, WITH 2-4 INCHES POSSIBLE IN THE LOWLANDS
AND 5-10 INCHES POSSIBLE IN THE MOUNTAINS. HYDROLOGIC IMPACTS
WILL BE SIGNIFICANT, BUT DETAILS ARE LISTED BELOW.
ADDITIONALLY, PERIODS OF INCREASED WIND WILL ACCOMPANY THE
SYSTEM, IN PARTICULAR ON MONDAY. HIGHER SNOW LEVELS ABOVE
5000-6000 FT WILL ALLOW FOR RAIN THROUGH THE PASSES AND SOME
SNOWMELT.
AVIATION
GENERALLY A MIX OF MVFR/IFR AND LOCALIZED LIFR AS SHOWERS
CONTINUE ACROSS WESTERN WASHINGTON THIS EVENING WITH
NORTHWESTERLY FLOW ALOFT. SUBSTANTIAL LOW LEVEL MOISTURE WILL
LIKELY KEEP DETERIORATED CONDITIONS THROUGHOUT THE REST OF THE
EVENING, ALONG WITH LIMITED VSBYS 3-6SM IN RAIN AND DRIZZLE.
MVFR/IFR WILL PERSIST INTO FRIDAY MORNING, WITH LOWER PRONE
LOCATIONS (KPWT, KOLM, AND EVEN KCLM) LIKELY SEEING LIFR
CONDITIONS. S/SW GENERALLY 6 TO 8 KNOTS THROUGHOUT THE EVENING
WILL INCREASE BY FRIDAY MORNING TO 10 TO 15 KNOTS.
KSEA...LIFR CEILINGS THIS EVENING WITH PERIODIC RAIN AND FOG.
CEILINGS WILL FLUCTUATE BETWEEN IFR AND LIFR THROUGHOUT THIS
EVENING, ALTHOUGH PROBABILITIES HAVE BEEN TRENDING MORE TOWARDS
IFR. WILL CONTINUE TO SEE VSBYS AROUND 4 TO 6 STATUTE MILES
FROM LIGHT RAIN AND DRIZZLE WITH IFR TO LIFR CONTINUING INTO THE
MORNING FRIDAY. S/SW WINDS 6 KT OR LESS THIS EVENING AND
OVERNIGHT WILL INCREASE TO 7 TO 12 KT ONCE AGAIN BY 17Z FRIDAY.
GUSTS UP TO 20 KNOTS CAN BE POSSIBLE THROUGHOUT FRIDAY
AFTERNOON.
MAZURKIEWICZ/15
MARINE
A WARM FRONT HAS MOVED THROUGH THE WATERS TODAY FOR
SOUTHERLY WINDS, ALTHOUGH THEY HAVE REMAINED UNDER ANY CRITERIA.
A STRONGER FRONT WILL MOVE OVER THE WATERS INTO FRIDAY, WHICH
WILL RESULT IN INCREASINGLY STRONG WESTERLY WINDS. LATEST
GUIDANCE HAS INCREASED SINCE THE PREVIOUS RUNS, WITH ALMOST
80-90% OF GALE GUSTS OVER THE COASTAL WATERS. THEREFORE, HAVE
UPGRADED THE GALE WATCH TO A GALE WARNING OVER ALL OF THE
COASTAL WATERS. GUIDANCE STILL SUGGESTS A 40 TO 50% CHANCE OF
GALE GUSTS IN THE INNER COASTAL WATERS, SO HAVE INCLUDED THEM AS
WELL. A STRONG WESTERLY PUSH IS ALSO EXPECTED IN THE STRAIT,
HAVE ALSO UPGRADED TO A GALE WARNING FOR ALL ENTRANCES OF THE
STRAIT FOR FRIDAY EVENING. ADDITIONALLY, OTHER INTERIOR WATERS
SUCH AS THE PUGET SOUND AND HOOD CANAL ZONES, AND THE NORTHERN
INTERIOR WATERS WILL SEE SMALL CRAFT WINDS DURING THIS TIME.
ADDITIONAL SYSTEMS LOOK TO MOVE IN OVER THE WEEKEND FOR SOME
ELEVATED AND WINDS AND SEAS, BUT LOOK TO REMAIN GENERALLY ON THE
MILD SIDE. A STRONGER SYSTEM ON MONDAY INTO TUESDAY LOOK TO
BRING WINDS BACK UP TO POSSIBLY GALE STRENGTH, ALONG WITH
ELEVATED SEAS.
COMBINED SEAS 5 TO 7 FEET WILL REMAIN THROUGH TONIGHT. SEAS
WILL START TO BUILD UPWARDS TO 10 FEET BY FRIDAY AFTERNOON,
BUILDING AGAIN TO 15 TO 17 FEET BY LATE FRIDAY EVENING INTO
SATURDAY MORNING.
MAZURKIEWICZ
HYDROLOGY
A SERIES OF WET WEATHER SYSTEMS WILL INCREASE THE THREAT OF
RIVER FLOODING THIS WEEKEND, ESPECIALLY INTO THE FIRST HALF OF
NEXT WEEK. WEST TO NORTHWESTERLY FLOW ALOFT WITH THE FIRST
SYSTEM ON FRIDAY WILL PUT THE AREA OF GREATEST PRECIPITATION IN
THE NORTH CENTRAL WASHINGTON CASCADES. SNOW LEVELS, AT THIS
TIME, WILL BE RISING OVER 5500 TO 6000 FEET.
AS THE FLOW ALOFT BECOMES MORE WESTERLY TO SOUTHWESTERLY THE
FLOOD THREAT WILL SHIFT TO THE FLOOD PRONE SKOKOMISH RIVER LATE
IN THE WEEKEND.
THERE'S STILL A WIDE VARIANCE IN THE POSSIBLE PRECIPITATION
AMOUNTS WITH AN ATMOSPHERIC RIVER SETTING UP THROUGH THE FIRST
PART OF NEXT WEEK, BUT CONFIDENCE IS INCREASING IN MODERATE TO
HEAVY RAINFALL ACROSS WESTERN WA, ESPECIALLY OVER THE OLYMPICS
AND CASCADES.
CONFIDENCE IS INCREASING THAT WE WILL SEE A WIDESPREAD RIVER
FLOODING EVENT ON OUR HANDS BEGINNING LATE MONDAY, THROUGHOUT
TUESDAY AND INTO WEDNESDAY, WITH MULTIPLE RIVERS FLOWING OFF THE
CASCADES AND THE OLYMPICS REACHING MINOR AND MODERATE FLOOD
STAGES (POTENTIALLY NEARING EVEN MAJOR FLOOD STAGE).
UNCERTAINTY STILL CONTINUES TO REMAIN IN REGARDS TO THE EXACT
FLOOD LEVELS AND STAGES THROUGH NEXT WEEK, AND AS SUCH IT WILL
BE CRITICAL TO MONITOR THE FORECASTS THROUGH THE NEXT SEVEN
DAYS.
THE SERIES OF WET SYSTEMS WILL START TO ELEVATE THE LANDSLIDE
RISK THROUGHOUT THE WEEKEND, INCREASING RAPIDLY EARLY NEXT WEEK
WITH THE ARRIVAL OF AN ATMOSPHERIC RIVER.
MAZURKIEWICZ
SEW WATCHES/WARNINGS/ADVISORIES
WA...COASTAL FLOOD ADVISORY FROM 4 AM TO 10 AM PST SATURDAY FOR
LOWLANDS OF WESTERN SKAGIT AND NORTHWESTERN SNOHOMISH
COUNTIES-LOWLANDS OF WESTERN WHATCOM COUNTY-SAN JUAN
COUNTY.
WINTER WEATHER ADVISORY FROM 7 PM FRIDAY TO 10 PM PST SATURDAY
FOR CASCADES OF SNOHOMISH AND NORTHERN KING COUNTIES.
COASTAL FLOOD ADVISORY FROM 9 AM TO 3 PM PST FRIDAY FOR
EASTERN STRAIT OF JUAN DE FUCA-GRAYS HARBOR COUNTY COAST-
NORTHERN WASHINGTON COAST-WESTERN STRAIT OF JUAN DE FUCA.
COASTAL FLOOD ADVISORY FROM 9 AM TO 3 PM PST SATURDAY FOR
GRAYS HARBOR COUNTY COAST.
PZ...GALE WARNING FROM 1 PM FRIDAY TO 4 AM PST SATURDAY FOR WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING FROM 1 PM FRIDAY TO 7 AM PST SATURDAY FOR CENTRAL
U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S.
WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 1 PM FRIDAY TO 10 AM PST SATURDAY
FOR NORTHERN INLAND WATERS INCLUDING THE SAN JUAN ISLANDS.
SMALL CRAFT ADVISORY FROM 1 PM FRIDAY TO 4 AM PST SATURDAY FOR
PUGET SOUND AND HOOD CANAL.
GALE WARNING FROM 10 AM FRIDAY TO 4 AM PST SATURDAY 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.
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