677
FXUS66 KSEW 190027
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
427 PM PST THU DEC 18 2025
SYNOPSIS
A SERIES OF WEATHER SYSTEMS WILL MOVE ACROSS WESTERN WASHINGTON
OVER THE NEXT WEEK, KEEPING THE UNSETTLED CONDITIONS ONGOING
ACROSS THE AREA. THESE UNSETTLED CONDITIONS COULD SEE PERIODS
OF LOWLAND RAIN, MOUNTAIN SNOW, AND BREEZY CONDITIONS AT TIMES
THROUGHOUT THE WEEKEND AND INTO THE EARLY HALF OF NEXT WEEK.
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
RECENT RADAR IMAGERY SHOWS A BULK OF RAINFALL OVER THE SOUTHERN
PORTIONS OF OUR AREA, WITH MOST OF THE HEAVIEST PRECIPITATION
FALLING OVER OREGON. AN UNSETTLED AND RAINY DAY IS STILL
EXPECTED OVER WESTERN WASHINGTON, WITH RAINFALL TOTALS GENERALLY
AROUND 0.25-0.50 OVER THE LOWLANDS, WITH LOCALLY HIGHER AMOUNTS
IN THE SOUTH SOUND. SNOW WILL CONTINUE IN THE MOUNTAINS, WITH
SNOW LEVELS RISING THIS AFTERNOON AND EVENING TO 6000 TO 7000
FEET. AS WARMER AIR MOVES ALOFT, CONTINUING TO MONITOR THE
POTENTIAL FOR A BRIEF PERIOD OF FREEZING RAIN AT THE PASSES, AS
SNOW CHANGES TO RAIN. UNCERTAINTY CONTINUES ON THE TIMING AND
THE DEPTH OF THE WARM LAYER OVER THE MOUNTAINS, AND HOW LONG
THAT LASTS FOR. SNOW LEVELS BEGIN TO QUICKLY PLUMMET LATE
TONIGHT THROUGH FRIDAY DOWNWARDS TO 1500 TO 2500 FEET, ALLOWING
FOR ACCUMULATIONS TO PILE UP WITHIN THE CASCADES. THEREFORE, A
WINTER STORM WARNING HAS BEEN ISSUED FOR MODERATE TO HEAVY
SNOWFALL AT TIMES, AS AREAS LIKE PARADISE AND BAKER COULD SEE
2-3 FEET, ALONG WITH SNOQUALMIE AND STEVENS SEEING A FOOT TO TWO
FEET OF SNOW THROUGHOUT THE WEEKEND.
SOUTHERLY WINDS WILL REMAIN ELEVATED THIS AFTERNOON, AROUND 25
TO 35 MPH, WITH OCCASIONAL GUSTS 45 TO 50 MPH POSSIBLE AT TIMES
THROUGHOUT THE INTERIOR THROUGH THIS EVENING. WINDS WILL EASE BY
TONIGHT. A SURGE OF WESTERLY WINDS THROUGH THE STRAIT WILL KEEP
AREAS LIKE WHIDBEY ISLAND BREEZY OVERNIGHT.
THE AFOREMENTIONED SYSTEM WILL CONTINUE TO SHIFT SOUTHWARD ON
FRIDAY, BUT CONDITIONS STILL REMAIN UNSETTLED OVER THE AREA,
WITH LOWLAND RAIN, MOUNTAIN SNOW, AND LOCALLY BREEZY CONDITIONS
AT TIMES. SNOW LEVELS WILL STAY AROUND 1500-2500 FEET, ALLOWING
FOR SNOWFALL TO CONTINUE IN THE MOUNTAINS.
LONG TERM /SUNDAY THROUGH THURSDAY/
ENSEMBLES ARE IN GENERALLY GOOD AGREEMENT IN UPPER LEVEL
TROUGHING OVER THE PACIFIC NORTHWEST THROUGH THE FIRST HALF OF
NEXT WEEK. ADDITIONAL SYSTEMS LOOK TO MOVE OVER THE AREA,
KEEPING UNSETTLED CONDITIONS OVER MOST OF THE AREA, WITH THESE
SYSTEMS GENERALLY REMAINING ON THE WEAKER SIDE. SNOW LEVELS LOOK
TO REMAIN BELOW PASS LEVEL, WHICH WOULD BRING MORE ROUNDS OF
MOUNTAIN SNOW, WITH RAIN EXPECTED IN THE LOWLANDS.
MAZURKIEWICZ
AVIATION
MOSTLY MVFR TO IFR THIS AFTERNOON IN LOW CEILINGS AND POCKETS OF
PATCHY FOG AS RAIN SHOWERS DECREASE IN COVERAGE. AN INCOMING FRONTAL
SYSTEM WILL BRING GUSTY WINDS TO THE WESTERN WASHINGTON TERMINALS
THROUGH THE EVENING, WITH SOUTHERLY/SOUTHWESTERLY GUSTS REACHING UP
TO 35-40 KT GENERALLY BETWEEN 23Z TO 3Z. WINDS WILL GRADUALLY EASE
OVERNIGHT AND THROUGHOUT THE TAF PERIOD BUT WILL REMAIN SOMEWHAT
GUSTY OVERNIGHT. CEILINGS MAY BRIEFLY LIFT TO LOW END VFR OVERNIGHT,
BUT A MAJORITY OF TERMINALS ARE EXPECTED TO STAY MVFR WITH CONTINUED
SHOWER ACTIVITY.
KSEA...IFR THIS AFTERNOON WITH RAIN SHOWERS AND FOG OVER THE
TERMINAL. A FRONTAL SYSTEM WILL BRING GUSTY SOUTHERLY WINDS TO THE
TERMINAL THIS AFTERNOON BETWEEN 23Z AND 3Z, WITH GUSTS PEAKING
AROUND 35 KT. CEILINGS MAY ALSO LOWER TO LOW END IFR AS THE FRONT
MOVES THROUGH IN HEAVIER RAIN SHOWERS. WINDS WILL SLOWLY TAPER
THROUGH THE FORECAST PERIOD, BUT WILL REMAIN GUSTY AROUND 20 KT
OVERNIGHT. CEILINGS WILL REMAIN BETWEEN LOW END VFR AND HIGH END
MVFR OVERNIGHT AS SHOWERS CONTINUE.
15
MARINE
A FRONTAL SYSTEM WILL CONTINUE TO PUSH ACROSS WESTERN WASHINGTON
WATERS TODAY, BRINGING ELEVATED WINDS AND SEAS. NUMEROUS HEADLINES
ARE OUT FOR AREA WATERS. THE STRONGEST WINDS ARE STILL ON TRACK TO
BE ALONG THE COASTAL WATERS AND ALONG THE EASTERN STRAIT. WINDS
ACROSS THE INTERIOR WATERS WILL ALSO BE GUSTY AS THE FRONT PUSHES
THROUGH. HELD OFF ON UPGRADING PUGET SOUND FROM A SMALL CRAFT
ADVISORY TO A GALE WARNING THIS EVENING. HOWEVER, LATEST HIGH-
RESOLUTION GUIDANCE DOES INDICATE THE POTENTIAL (70-90%) OF
OCCASIONAL GALE GUSTS, WITH GUSTS UP 40 KT BETWEEN THE APPROXIMATE
HOURS OF 1500-1900 PST. IN THE WAKE OF THE FRONTAL PASSAGE, A STRONG
WESTERLY PUSH OF GALES IS EXPECTED ACROSS THE STRAIT OF JUAN DE FUCA
THIS EVENING, WITH WINDS GRADUALLY SUBSIDING EARLY FRIDAY MORNING.
THE OVERALL PATTERN REMAINS ACTIVE ACROSS THE WEEKEND AND INTO EARLY
NEXT WEEK, AS ADDITIONAL SYSTEMS ARE EXPECTED TO MOVE ACROSS AREA
WATERS.
SEAS AT 13-16 FT THIS AFTERNOON WILL GRADUALLY DECREASE INTO THE
WEEKEND TO AROUND 10 FT. ADDITIONAL SYSTEMS EARLY IN THE WEEK WILL
LEAD TO ELEVATED SEAS ACROSS THE COASTAL WATERS.
29
HYDROLOGY
A WEATHER SYSTEM CONTINUES TO MOVE EAST OF THE CASCADES
THIS AFTERNOON. 12 HOUR QPF AMOUNTS IN THE MOUNTAINS RANGE 0.50-1.0"
WITH UP TO 2" IN THE CASCADES OF LEWIS COUNTY AND THE OLYMPICS.
ADDITIONAL PRECIPITATION WILL CONTINUE AT TIMES FRIDAY INTO
SATURDAY, PARTICULARLY OVER THE CASCADES. HOWEVER, SNOW LEVELS WILL
FALL TO NEAR 1500 TO 2000 FEET ON FRIDAY, RESULTING IN SNOWFALL FOR
THE MOUNTAINS ABOVE THIS LEVEL.
ONGOING RIVER FLOODING CONTINUES FOR SELECT RIVERS OFF THE CASCADES
FROM KING COUNTY SOUTHWARDS. FOR RIVERS DOWNSTREAM OF DAMS, DAM
OPERATIONS TO MAINTAIN A SAFE FLOOD POOL FOR AREA DAMS COULD
MAINTAIN ELEVATED FLOW LEVELS OR THEY COULD RAISE OR LOWER LEVELS
DOWNSTREAM OF THE DAMS. DAM REGULATION CHANGE RAPIDLY.
ADDITIONAL RISES ON RIVERS ARE EXPECTED FRIDAY INTO SATURDAY,
ESPECIALLY FOR RIVERS IN LEWIS COUNTY, DUE TO THE ONGOING
PRECIPITATION. FOR THAT REASON, THE FLOOD WATCH HAS BEEN UPDATED TO
INCLUDE LEWIS COUNTY INTO THE WEEKEND. THE FLOOD WATCH REMAINS FOR
KING, PIERCE, THURSTON, AND GRAYS HARBOR COUNTY DUE TO ELEVATED
RIVER LEVELS, ESPECIALLY RIVERS DOWNSTREAM OF DAM OPERATIONS.
THE LANDSLIDE THREAT WILL REMAIN HIGH THROUGH AT LEAST FRIDAY.
JD
SEW WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY UNTIL 11 PM PST THIS EVENING FOR ISLAND COUNTY-
LOWLANDS OF WESTERN SKAGIT AND NORTHWESTERN SNOHOMISH
COUNTIES-LOWLANDS OF WESTERN WHATCOM COUNTY-SAN JUAN
COUNTY.
WINTER WEATHER ADVISORY UNTIL 7 PM PST THIS EVENING FOR
CASCADES OF PIERCE AND LEWIS COUNTIES-CASCADES OF
SNOHOMISH AND NORTHERN KING COUNTIES-CASCADES OF SOUTHERN
KING COUNTY-CASCADES OF WHATCOM AND SKAGIT COUNTIES.
WINTER STORM WARNING FROM 4 AM FRIDAY TO 4 PM PST SATURDAY FOR
CASCADES OF PIERCE AND LEWIS COUNTIES-CASCADES OF
SNOHOMISH AND NORTHERN KING COUNTIES-CASCADES OF SOUTHERN
KING COUNTY-CASCADES OF WHATCOM AND SKAGIT COUNTIES.
FLOOD WATCH THROUGH FRIDAY AFTERNOON FOR CASCADES OF PIERCE
AND LEWIS COUNTIES-CASCADES OF SNOHOMISH AND NORTHERN
KING COUNTIES-CASCADES OF SOUTHERN KING COUNTY-CITY OF
SEATTLE-EASTSIDE-FOOTHILLS AND VALLEYS OF CENTRAL KING
COUNTY-FOOTHILLS AND VALLEYS OF PIERCE AND SOUTHERN KING
COUNTIES-FOOTHILLS AND VALLEYS OF SNOHOMISH AND NORTHERN
KING COUNTIES-FOOTHILLS AND VALLEYS OF THURSTON AND LEWIS
COUNTIES-FOOTHILLS OF THE WESTERN AND SOUTHERN OLYMPIC
PENINSULA-GRAYS HARBOR COUNTY COAST-LOWER CHEHALIS RIVER
VALLEY-LOWLANDS OF LEWIS AND SOUTHERN THURSTON COUNTIES-
LOWLANDS OF PIERCE AND SOUTHERN KING COUNTIES-MIDDLE
CHEHALIS RIVER VALLEY-OLYMPIA AND SOUTHERN PUGET SOUND-
OLYMPICS-SHORELINE / LYNNWOOD / SOUTH EVERETT AREA-
WILLAPA AND BLACK HILLS.
WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR CITY OF SEATTLE-
DOWNTOWN EVERETT / MARYSVILLE AREA-EASTERN KITSAP COUNTY-
EASTSIDE-FOOTHILLS AND VALLEYS OF CENTRAL KING COUNTY-
FOOTHILLS AND VALLEYS OF PIERCE AND SOUTHERN KING
COUNTIES-FOOTHILLS AND VALLEYS OF THURSTON AND LEWIS
COUNTIES-GRAYS HARBOR COUNTY COAST-LOWLANDS OF LEWIS AND
SOUTHERN THURSTON COUNTIES-LOWLANDS OF PIERCE AND
SOUTHERN KING COUNTIES-NORTHERN WASHINGTON COAST-OLYMPIA
AND SOUTHERN PUGET SOUND-SHORELINE / LYNNWOOD / SOUTH
EVERETT AREA-WILLAPA AND BLACK HILLS.
PZ...SMALL CRAFT ADVISORY UNTIL 7 PM PST THIS EVENING FOR GRAYS
HARBOR BAR-PUGET SOUND AND HOOD CANAL.
SMALL CRAFT ADVISORY FROM 4 AM TO 4 PM PST FRIDAY FOR GRAYS
HARBOR BAR.
SMALL CRAFT ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 7 PM PST THIS EVENING FOR WEST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 4 AM PST FRIDAY FOR CENTRAL U.S. WATERS
STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 4 AM PST FRIDAY FOR EAST ENTRANCE U.S.
WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 7 PM PST THIS EVENING FOR ADMIRALTY INLET-
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-
NORTHERN INLAND WATERS INCLUDING THE SAN JUAN ISLANDS.
SMALL CRAFT ADVISORY FROM 4 AM TO 10 PM PST FRIDAY 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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