649
FXUS66 KSEW 191204
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
404 AM PST FRI DEC 19 2025
SYNOPSIS
A SERIES OF WEATHER SYSTEMS MOVING ACROSS THE REGION WILL BRING
PERIODS OF LOWLAND RAIN, MOUNTAIN SNOW, AND BREEZY CONDITIONS
TO WESTERN WASHINGTON AT TIMES THROUGHOUT THE NEXT WEEK.
SHORT TERM /TODAY THROUGH SUNDAY/
SHOWERS PERSIST ACROSS THE AREA THIS MORNING IN THE WAKE OF A
SYSTEM THAT MOVED INTO THE REGION ON THURSDAY, WITH LATEST RADAR
INDICATING A CONVERGENCE ZONE DEVELOPING ACROSS KING COUNTY.
LATEST OBSERVATIONS AS OF 2 AM PT HAVE INDICATED THAT IT'S
STILL RAINING AT SNOQUALMIE PASS THIS MORNING, BUT EXPECT RAIN
TO TRANSITION OVER TO SNOW WITHIN THE NEXT COUPLE OF HOURS AS
TEMPERATURES CONTINUE TO DROP AND SNOW LEVELS CONTINUE TO FALL
TO 1500-2000 FT. SHOWER ACTIVITY WILL CONTINUE THROUGH MUCH OF
THE DAY TODAY AND WILL BRING RAINFALL AMOUNTS OF 0.10-0.25
INCHES TO MOST LOWLAND LOCATIONS. PORTIONS OF THE CENTRAL SOUND
LOWLANDS, INCLUDING SEATTLE, LOOK TO REMAIN SHADOWED, AND WILL
LIKELY SEE LOWER RAINFALL AMOUNTS OF A COUPLE HUNDREDTHS OF AN
INCH. SNOW ACCUMULATIONS WILL START TO RAMP UP ACROSS THE
MOUNTAINS THROUGHOUT THE DAY AND WILL CONTINUE HEADING INTO
SATURDAY.
A WINTER STORM WARNING REMAINS IN EFFECT FOR THE CASCADES
THROUGH SATURDAY AFTERNOON FOR SNOW ACCUMULATIONS EXPECTED TO BE
BETWEEN 1-2 FT FOR THE PASSES AND UP TO 2 TO 3 FT FOR LOCATIONS
LIKE PARADISE AND MOUNT BAKER. SHOWER ACTIVITY WILL CONTINUE
THROUGH MUCH OF THE DAY SATURDAY, KEEPING CONDITIONS RATHER
UNSETTLED ACROSS WESTERN WASHINGTON.
A SHORTWAVE WILL THEN MOVE ACROSS THE REGION ON SUNDAY AND WILL
BRING YET ANOTHER ROUND OF BREEZY SOUTHERLY WINDS, LOWLAND
RAIN, AND MOUNTAIN SNOW. THE COOLER WEATHER PATTERN WILL
CONTINUE INTO EARLY NEXT WEEK.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
CONDITIONS LOOK TO REMAIN ACTIVE THROUGH MUCH OF THE NEXT WEEK
AS ENSEMBLES REMAIN IN GOOD AGREEMENT OF AN UPPER LEVEL TROUGH
DIGGING ACROSS THE NORTHEASTERN PACIFIC AND SWINGING ADDITIONAL
DISTURBANCES INTO THE REGION. THIS WOULD CONTINUE TO BRING
PERIODS OF LOWLAND RAIN AND MOUNTAIN SNOW TO WESTERN WASHINGTON
THROUGH MUCH OF THE NEXT WEEK. THE WEATHER PATTERN WILL ALSO
ALLOW FOR A TREND TOWARDS COOLER TEMPERATURES, ESPECIALLY DURING
THE OVERNIGHT PERIOD, WHERE WE MAY START TO SEE MORNING LOWS
APPROACH FREEZING IN SPOTS BY MIDWEEK.
14
AVIATION
ZONAL FLOW ALOFT BECOMING MORE NORTHWESTERLY THIS AFTERNOON BEFORE
RETURNING TO ZONAL BY SATURDAY MORNING. SURFACE WINDS AROUND THE
AREA ALL GENERALLY HAVE A SOUTHERLY COMPONENT AND WHILE MOST
TERMINALS ARE FAVORING A SOUTH TO SLIGHTLY SOUTHWESTERLY DIRECTION,
A HANDFUL ARE SEEING MORE SOUTHEASTERLY WINDS. SPEEDS AT MOST
TERMINALS GENERALLY RUNNING 4-8 KTS WHILE MORE WIND PRONE LOCATIONS
LIKE HQM AND PWT ARE FAVORING 8-12 KTS. MORE WIDESPREAD SPEEDS OF 8-
12 KTS EXPECTED BY LATE MORNING/EARLY AFTERNOON AND LIKELY TO REMAIN
THERE FOR THE REMAINDER OF THE TAF PERIOD.
VFR CONDITIONS AREA-WIDE THIS EARLY MORNING, SAVE FOR PAE...BUT JUST
BARELY. AS MORE WIDESPREAD SHOWERS MOVE INTO THE AREA BY LATE THIS
MORNING/EARLY THIS AFTERNOON, CIGS WILL SINK INTO WIDESPREAD MVFR.
THE ELEVATED WINDS WILL LIKELY OFFER SOME PUSH BACK, KEEPING
LOCATIONS MORE PRONE TO LOWER CIGS AT LEAST WITHIN LOW-END MVFR.
SOME SLIGHT RECOVERY IN THE LATE AFTERNOON AND EARLY EVENING IS
POSSIBLE, RETURNING SOME SITES TO VFR CONDITIONS, BUT BY TONIGHT
THERE WILL BE PLENTY OF LOW-LEVEL MOISTURE TO DRAG CIGS BACK DOWN TO
MVFR FOR THE REMAINDER OF THE TAF PERIOD.
KSEA...ABOVE DISCUSSION AND TRENDS APPLY. VFR CONDITIONS THIS
MORNING BEFORE DROPPING TO MVFR AROUND 17Z. SOME RECOVERY TO LOW-END
VFR AROUND 00Z THIS AFTERNOON BEFORE RETURNING TO MVFR TONIGHT.
SOUTH-SOUTHWESTERLY WINDS THROUGHOUT THE PERIOD WITH SPEEDS 4-8 KTS
THROUGH AROUND 18Z, INCREASING TO 8-12 KTS FOR THE REMAINDER OF THE
PERIOD.
18
MARINE
WINDS WILL CONTINUE TO EASE ACROSS THE AREA WATERS OVERNIGHT IN
THE WAKE OF A SYSTEM THAT MOVED ACROSS THE REGION ON THURSDAY.
EXPECT SOUTHERLY WINDS TO REMAIN BREEZY ACROSS PUGET SOUND AND
THE COASTAL WATERS THROUGH THE DAY TODAY, HOWEVER, WHERE SMALL
CRAFT ADVISORIES ARE IN EFFECT. PROBABILITIES FOR WINDS
REACHING SMALL CRAFT THRESHOLDS WERE LESS THAN 50 PERCENT FOR
THE INTERIOR WATERS FROM ADMIRALTY INLET NORTHWARD, SO HAVE
LEFT THESE ZONES OUT OF ADVISORIES FOR NOW. WHILE OCCASIONAL
SMALL CRAFT GUSTS WILL BE POSSIBLE AT TIMES, THE AERIAL EXTENT
OF THESE WINDS REMAINS SMALL.
A WEAKENING FRONTAL SYSTEM WILL THEN MOVE INTO THE AREA WATERS
ON SUNDAY, FOLLOWED BY A STRONGER SYSTEM ON MONDAY. CONDITIONS
WILL REMAIN ACTIVE ACROSS THE AREA WATERS THROUGH MUCH OF THE
NEXT WEEK, WITH ADDITIONAL HEADLINES LIKELY.
SEAS BETWEEN 13-15 FT WILL CONTINUE TO GRADUALLY SUBSIDE TOWARDS
8-10 FT THROUGH THE WEEKEND. SEAS WILL LIKELY INCREASE AGAIN
TOWARDS 12-15 FT BY EARLY NEXT WEEK AS ADDITIONAL SYSTEMS MOVE
ACROSS THE REGION.
14
HYDROLOGY
ADDITIONAL PRECIPITATION WILL CONTINUE AT TIMES TODAY INTO SATURDAY,
PARTICULARLY OVER THE CASCADES AS SHOWERS REMAIN IN THE FORECAST.
HOWEVER, SNOW LEVELS WILL FALL TO NEAR 1500 TO 2000 FEET TODAY,
RESULTING IN SNOWFALL FOR THE MOUNTAINS ABOVE THIS LEVEL. SOME
RIVERS CONTINUE TO SEE SOME RISES DUE TO YESTERDAY'S PRECIP, HOWEVER
THOSE THAT DID SEE RISES HAVE GENERALLY CRESTED AT THIS POINT AND
ARE SLOWLY STARTING TO FALL. THE ONE THAT HASN'T, THE CHEHALIS AT
PORTER, HAS RISEN TO JUST A TENTH OF AN INCH UNDER FLOOD STAGE AND
IS FORECAST TO SLIGHTLY NUDGE UPWARD JUST ENOUGH TO MEET CRITERIA.
THAT SAID, A FLOOD WARNING HAS BEEN ISSUED HERE AND WILL CONTINUE TO
MONITOR.
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 REMAIN POSSIBLE INTO SATURDAY, ESPECIALLY
FOR RIVERS IN LEWIS COUNTY, DUE TO THE ONGOING PRECIPITATION FROM A
SYSTEM MOVING JUST TO OUR SOUTH. FOR THESE REASONS, THE FLOOD WATCH,
INCLUDING LEWIS COUNTY, WILL REMAIN IN PLACE INTO THE
WEEKEND...WHICH INCLUDES KING, PIERCE, THURSTON, GRAYS HARBOR AND
LEWIS COUNTIES.
THE LANDSLIDE THREAT WILL REMAIN HIGH THROUGH INTO THE WEEKEND.
JD
SEW WATCHES/WARNINGS/ADVISORIES
WA...WINTER STORM WARNING FROM 4 AM EARLY THIS MORNING 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 SATURDAY MORNING 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.
PZ...SMALL CRAFT ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR GRAYS
HARBOR BAR.
GALE WARNING UNTIL 4 AM PST EARLY THIS MORNING FOR CENTRAL
U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S.
WATERS STRAIT OF JUAN DE FUCA-WEST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 4 AM PST EARLY THIS MORNING FOR
ADMIRALTY INLET-NORTHERN INLAND WATERS INCLUDING THE SAN
JUAN ISLANDS-PUGET SOUND AND HOOD CANAL.
SMALL CRAFT ADVISORY UNTIL 10 PM PST THIS EVENING 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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