990
FXUS66 KSEW 100551 AAA
AFDSEW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SEATTLE WA
951 PM PST TUE DEC 9 2025
SYNOPSIS
A STRONG ATMOSPHERIC SYSTEM WILL CONTINUE TO BRING PERIODS OF
HEAVY RAIN AND GUSTY WINDS TO WESTERN WASHINGTON THROUGH
WEDNESDAY. WIDESPREAD SIGNIFICANT RIVER FLOODING HAS BEEN UNDERWAY
AND IS EXPECTED TO CONTINUE THROUGH MUCH OF THE WEEK. MINOR
COASTAL FLOODING DUE TO ASTRONOMICAL HIGH TIDES WILL ALSO POSE
CONCERNS FOR THE NORTHERN SALISH SEA COASTLINES THROUGH MUCH OF
THE WEEK. WET AND UNSETTLED CONDITIONS WILL CONTINUE THROUGH THE
THE REMAINDER OF THE WEEK.
SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/
A STRONG ATMOSPHERIC SYSTEM IS WELL UNDERWAY ACROSS THE PACIFIC
NORTHWEST. THE AXIS OF MOISTURE HAS SHIFTED TO THE SOUTH THIS
AFTERNOON WITH MOST AREAS NORTHWARD OF CHEHALIS SEEING DRIER
CONDITIONS, WHICH HAS PROVIDED A BRIEF LULL IN RAINFALL ACROSS
THE REGION. HOWEVER, FLOODING IS STILL EXPECTED DESPITE A BRIEF
DECREASE IN RAINFALL. HEAVY PRECIPITATION WILL FILL BACK IN
LATER THIS AFTERNOON INTO THE EARLY HOURS OF THE EVENING AS THE
ATMOSPHERIC RIVER SHIFTS NORTHWARD AND TAKES DIRECT AIM ONCE
AGAIN AT WESTERN WASHINGTON.
THIS SECOND WAVE OF PRECIPITATION WILL HAVE A LONGER DURATION
OF RAIN, WITH LATEST GUIDANCE TRENDING A LITTLE BIT WETTER THAN
PREVIOUS FORECASTS. THIS LONGER DURATION RAINFALL WILL KEEP
RIVERS ELEVATED, WITH ANOTHER ROUND OF RISES ON AREA RIVERS -
POTENTIALLY EVEN PEAKING HIGHER THAN THE PREVIOUS ROUND.
SIGNIFICANT RIVER FLOODING IS EXPECTED TO CONTINUE OVER THE NEXT
SEVERAL DAYS. THE FOLLOWING KEY MESSAGES WITH THIS ATMOSPHERIC
RIVER SYSTEM ARE OUTLINED BELOW:
* HEAVY RAIN: DESPITE A DECREASE IN RAINFALL THIS AFTERNOON,
THE ATMOSPHERIC RIVER SYSTEM WILL BRING ANOTHER WAVE OF HEAVY
RAIN TO WESTERN WASHINGTON BY THIS EVENING, CONTINUING THROUGH
WEDNESDAY NIGHT. WHILE AREAS EAST OF THE OLYMPICS WILL LIKELY
SEE SOME SHADOWING AT THE ONSET OF PRECIPITATION ONCE AGAIN
THIS AFTERNOON, HEAVY RAIN WILL CONTINUE TO CAUSE FLOODING
CONCERNS TO AREA RIVERS, URBAN AREAS, AND AREAS WITH POOR
DRAINAGE. FORECAST MODELS REMAIN CONSISTENT WITH RAINFALL
FORECASTS, SHOWING AN ADDITIONAL 2 TO 3 INCHES OF RAIN ACROSS
THE LOWLANDS AND 5 TO 8 INCHES OVER THE MOUNTAINS THROUGH LATE
WEDNESDAY. MANY AREA RIVERS HAVE ENTERED MAJOR FLOOD STAGE,
WITH ANOTHER WAVE OF RISES EXPECTED TONIGHT INTO THURSDAY. FOR
MORE DETAILS, SEE THE HYDROLOGY SECTION BELOW.
* WINDS: ANOTHER WAVE OF BREEZY WINDS CAN BE EXPECTED ALONGSIDE
THE SECOND WAVE OF RAINFALL. WIND GUSTS ARE EXPECTED TO REACH
40-45 MPH ACROSS THE REGION LATE THIS EVENING AS THE SECOND
WAVE OF THE ATMOSPHERIC RIVER SYSTEM PUSHES INTO THE REGION.
WINDS WILL REMAIN BREEZY THROUGH WEDNESDAY.
* COASTAL FLOODING: MINOR COASTAL FLOODING REMAINS POSSIBLE
ALONG THE NORTHERN SALISH SEA COASTLINES DURING WEDNESDAYS
HIGH ASTRONOMICAL TIDE. WHILE THE TIDES WILL GENERALLY REMAIN
BELOW OR NEARING THRESHOLDS, HEIGHTENED RIVER FLOWS OR WIND
EFFECTS COULD EXACERBATE INUNDATION IN SOME AREAS AROUND HIGH
TIDE.
IN ADDITION, SNOW LEVELS ARE GENERALLY NEAR 3500-4000 FEET OVER
THE MOUNTAINS, WHICH HAS RESULTED IN MINOR ACCUMULATING SNOW
THIS AFTERNOON GENERALLY ABOVE 4500 FEET. SNOW LEVELS WILL BEGIN
TO RISE RAPIDLY BY THIS EVENING TO 7000 TO 9000 FEET AS THE
ATMOSPHERIC RIVER SHIFTS NORTHWARD.
THE RETURNING SURGE OF MOISTURE LATER THIS EVENING WILL BRING
WARMER TEMPERATURES AND HIGHER SNOW LEVELS THROUGHOUT THE
REMAINDER OF THE WEEK. TEMPERATURES WILL PEAK WELL ABOVE NORMAL
MOST DAYS THIS WEEK, WITH TEMPERATURES IN THE LOW TO UPPER 50S
ACROSS THE LOWLANDS.
LONG TERM /FRIDAY THROUGH TUESDAY/
FORECAST MODELS REMAIN IN GOOD AGREEMENT THAT UNSETTLED
CONDITIONS WILL CONTINUE THROUGH THE REMAINDER OF THE WEEK AND
INTO EARLY NEXT WEEK AS ADDITIONAL SYSTEMS ARE SET TO CROSS OVER
THE PACIFIC NORTHWEST. IT IS LIKELY THAT IMPACTS FROM
SIGNIFICANT RIVER FLOODING WILL LINGER THROUGH THURSDAY AND EVEN
INTO THE WEEKEND FOR MANY AREAS. LATEST ENSEMBLE DATA HAVE
SHOWN POTENTIALLY MORE SYSTEMS ON THE WAY THROUGH THE EARLY PART
OF NEXT WEEK, STARTING ON MONDAY, WHICH WILL KEEP THE PATTERN
WET AND ACTIVE.
15/MAZURKIEWICZ
AVIATION
DETERIORATING CONDITIONS ARE UNDERWAY AS THE NEXT WAVE OF MOISTURE
BEGINS PUSHING INTO THE REGION. CEILINGS WILL TREND TOWARDS MVFR
THROUGH THE NIGHT WITH REDUCED VISIBILITIES DUE TO MODERATE TO HEAVY
RAIN (DOWN TO AS LITTLE AS 2 SM). CEILINGS APPROACH IFR/LIFR
WEDNESDAY MORNING AND VISIBILITIES DOWN TO 1-3 SM WITH MIST. THIS
LOOKS TO LAST MUCH OF WEDNESDAY AND INTO THURSDAY WITH MARGINAL
IMPROVEMENTS. EXPECT WINDS TO PICK UP OUT OF THE SOUTHWEST TONIGHT
THROUGH WEDNESDAY, WITH SUSTAINED WINDS AT 15-20 KT GUSTING TO 30-35
KT (POSSIBLY UP TO 40 KT ALONG THE COAST), THEN DIMINISHING LATE
WEDNESDAY. THE STRONGEST WINDS WILL BE IN THE SOUTHERN/CENTRAL
TERMINALS. SOME LOW-SPEED WIND SHEAR CAN'T BE RULED OUT WITH THE
INITIAL ONSET OF WINDS, BUT IS PRIMARILY EXPECTED TO BE MORE OF A
LOW-LEVEL TURBULENCE ISSUE (WITH WINDS ALOFT STAYING OUT OF THE
SOUTHWEST BELOW 2,000 FT).
KSEA...MVFR CEILINGS THIS EVENING WILL PERSIST OVERNIGHT WITH PERIODS
OF REDUCED VISIBILITIES DURING PERIODS OF HEAVY PRECIPITATION. THE
HEAVIER RAIN RATES ARE EXPECTED AROUND THE TERMINAL, SO WILL LIKELY
SEE LESSER IMPACTS TO VISIBILITIES COMPARED TO ALTERNATES. CEILINGS
WILL TREND DOWN TO IFR WEDNESDAY MORNING AND PERSIST THROUGH MUCH OF
THE DAY. WINDS REMAIN OUT OF THE SOUTHWEST AT AROUND 5-10 KT THROUGH
THE EVENING, INCREASING AROUND 08Z TO 15-20 KT WITH GUSTS TO 25 TO
30 KT THROUGH THE NIGHT, WITH GUSTS INCREASING FURTHER TO 30 TO 40
KT THROUGH WEDNESDAY AFTERNOON, BEFORE DECREASING AGAIN.
MNF
MARINE
THE SECOND FRONTAL SYSTEM WITH AN ATMOSPHERIC RIVER WILL ARRIVE
LATER THIS EVENING AND PERSIST INTO WEDNESDAY. MODERATE TO HEAVY
RAIN OVER THE WATERS (ALONG WITH LOWER CEILINGS AND MIST) MAY REDUCE
VISIBILITIES AT TIMES. SOUTH WINDS WILL BEGIN TO INCREASE TONIGHT,
AND PERSIST INTO MUCH OF WEDNESDAY. WEST WINDS WILL FOLLOW IN THE
STRAIT OF JUAN DE FUCA LATE WEDNESDAY EVENING. MOST WATERS ARE UNDER
SMALL CRAFT ADVISORIES FOR THE BREEZY WINDS. THE INNER COASTAL
WATERS AND WEST/CENTRAL STRAIT OF JUAN DE FUCA WERE UPGRADED TO GALE
WARNINGS WITH FREQUENT GUSTS TO 35 KT LIKELY THIS EVENING. PUGET
SOUND WATERS IS THE NEXT AREA BEING MONITORED FOR A POSSIBLE UPGRADE
TO A GALE WARNING (BUT CONFIDENCE WAS NOT HIGH ENOUGH TO ISSUE IT
THIS AFTERNOON). WINDS WILL DECREASE BELOW ANY CONCERN THURSDAY
THROUGH EARLY NEXT WEEK, WHERE ANOTHER SYSTEM MAY PRODUCE GUSTY
SMALL CRAFT WINDS FOR THE COASTAL WATERS, AND INTERIOR WATERS.
SEAS OF 8-12 FT WILL CONTINUE THROUGH THURSDAY, DECREASING TO 6 TO 8
FT SUNDAY, INCREASING TO 10-13 FT EARLY NEXT WEEK.
HPR
HYDROLOGY
A STRONG ATMOSPHERIC ATMOSPHERIC WILL CONTINUE TO SHIFT BACK
NORTH THROUGH THE PACIFIC NORTHWEST TONIGHT THROUGH LATE
WEDNESDAY. THIS WILL BRING ANOTHER ROUND OF SIGNIFICANT HEAVY
RAINFALL ACROSS THE AREA. 48-HOUR PRECIPITATION AMOUNTS ENDING
WEDNESDAY NIGHT WILL LIKELY REACH 2 TO 4 INCHES ACROSS THE
LOWLANDS, WITH 6 TO 10 INCHES OVER THE OLYMPICS AND CASCADES
WITH LOCALLY HIGHER AMOUNTS OVER 12 INCHES IN THE THE CENTRAL
AND SOUTHERN CASCADES.
MOST RIVERS ACROSS WESTERN WASHINGTON WILL BE AFFECTED BY THIS
SECOND WAVE AND MANY FLOOD WARNINGS REMAIN IN EFFECT. CONSULT
WEATHER.GOV/SEATTLE FOR THE LATEST. WHILE SOME UNCERTAINTY DOES
STILL REMAIN IN REGARDS TO THE EXACT FLOOD LEVELS AND STAGES, MANY
RIVER FORECAST POINTS ARE PROJECTED TO REACH MAJOR FLOOD STAGE
IN THE DAYS AHEAD AND SEVERAL MAY EVEN APPROACH OR EXCEED THE
PREVIOUS FLOODS OF RECORD. THEREFORE, IT WILL BE CRITICAL TO
MONITOR THE FORECASTS NOW AND THROUGH THE NEXT SEVEN DAYS.
ADDITIONAL PRECIPITATION IS ALSO POSSIBLE THURSDAY AND FRIDAY,
WHICH MAY KEEP RIVERS ELEVATED HEADING INTO THE WEEKEND.
A FLOOD WATCH REMAINS IN EFFECT ACROSS ALL OF WESTERN
WASHINGTON THROUGH FRIDAY.
WITH THE WET ANTECEDENT SOIL CONDITIONS, THE LANDSLIDE THREAT
ACROSS THE REGION WILL INCREASE WITH THIS SYSTEM. POTENTIAL HAS
ALSO INCREASED FOR DEBRIS FLOWS OVER AREA BURN SCARS, WHICH WILL
CONTINUE TO BE MONITORED.
URBAN AND SMALL STREAM FLOODING, AS WELL AS AREAS WITH POOR
DRAINAGE, SHOULD BE ALERT TO THE POTENTIAL FOR LOCALIZED NUISANCE
FLOODING AND PONDING ON ROADWAYS. LOW WATER CROSSINGS MAY BECOME
IMPACTED OR IMPASSABLE.
SEW WATCHES/WARNINGS/ADVISORIES
WA...FLOOD WATCH THROUGH FRIDAY AFTERNOON 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-CITY OF SEATTLE-DOWNTOWN
EVERETT / MARYSVILLE AREA-EASTERN KITSAP COUNTY-EASTERN
STRAIT OF JUAN DE FUCA-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 AND VALLEYS OF THE
NORTH CASCADES-FOOTHILLS OF THE WESTERN AND SOUTHERN
OLYMPIC PENINSULA-GRAYS HARBOR COUNTY COAST-ISLAND COUNTY-
LAKE CRESCENT AREA INCLUDING US 101-LOWER CHEHALIS RIVER
VALLEY-LOWLANDS OF LEWIS AND SOUTHERN THURSTON COUNTIES-
LOWLANDS OF PIERCE AND SOUTHERN KING COUNTIES-LOWLANDS OF
WESTERN SKAGIT AND NORTHWESTERN SNOHOMISH COUNTIES-
LOWLANDS OF WESTERN WHATCOM COUNTY-MIDDLE CHEHALIS RIVER
VALLEY-NORTHERN HOOD CANAL-NORTHERN WASHINGTON COAST-
OLYMPIA AND SOUTHERN PUGET SOUND-OLYMPICS-PORT TOWNSEND
AREA-SAN JUAN COUNTY-SHORELINE / LYNNWOOD / SOUTH EVERETT
AREA-SOUTHERN HOOD CANAL-WESTERN STRAIT OF JUAN DE FUCA-
WILLAPA AND BLACK HILLS.
COASTAL FLOOD ADVISORY FROM 7 AM TO 1 PM PST WEDNESDAY FOR
LOWLANDS OF WESTERN SKAGIT AND NORTHWESTERN SNOHOMISH
COUNTIES-LOWLANDS OF WESTERN WHATCOM COUNTY-SAN JUAN
COUNTY.
WIND ADVISORY UNTIL 10 PM PST WEDNESDAY FOR CITY OF SEATTLE-
DOWNTOWN EVERETT / MARYSVILLE AREA-EASTERN KITSAP COUNTY-
EASTSIDE-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-NORTHERN WASHINGTON COAST-OLYMPIA
AND SOUTHERN PUGET SOUND-SHORELINE / LYNNWOOD / SOUTH
EVERETT AREA-SOUTHERN HOOD CANAL-WILLAPA AND BLACK HILLS.
PZ...SMALL CRAFT ADVISORY UNTIL 10 PM PST WEDNESDAY FOR ADMIRALTY
INLET-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-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA-GRAYS HARBOR BAR-NORTHERN INLAND
WATERS INCLUDING THE SAN JUAN ISLANDS-PUGET SOUND AND
HOOD CANAL.
GALE WARNING UNTIL 10 PM PST WEDNESDAY FOR CENTRAL U.S. WATERS
STRAIT OF JUAN DE FUCA-COASTAL WATERS FROM CAPE FLATTERY
TO JAMES ISLAND OUT 10 NM-COASTAL WATERS FROM JAMES
ISLAND TO POINT GRENVILLE OUT 10 NM-COASTAL WATERS FROM
POINT GRENVILLE TO CAPE SHOALWATER OUT 10 NM-WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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