850
FXUS66 KSEW 051758
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
958 AM PST FRI DEC 5 2025
SYNOPSIS
THE WEATHER PATTERN HAS TRANSITIONED INTO AN ACTIVE PHASE AS A
SERIES OF SYSTEM BRING RAIN, HIGH ELEVATION SNOW AND WIND INTO
THE REGION THROUGH THE END OF THE WEEKEND. A STRONG ATMOSPHERIC
RIVER IS STILL ON TRACK TO REGION THE AREA BY MONDAY AND LAST
INTO AT LEAST THE MIDWEEK TIME FRAME. THIS SYSTEM WILL BRING
VERY SIGNIFICANT RAINFALL AND LIKELY HYDROLOGIC IMPACTS. COASTAL
FLOODING DUE TO HIGHER ASTRONOMICAL TIDES WILL REMAIN MINOR INTO
EARLY NEXT WEEK.
SHORT TERM /TODAY THROUGH SUNDAY/
RAIN CONTINUES TO MOVE INTO THE AREA FROM THE NORTHWEST THIS
MORNING, WITH THE HEAVIEST PRECIPITATION CURRENTLY FOCUSED ON
THE NORTHERN AND SOUTHERN CASCADES. OVERALL, THE FORECAST
REMAINS LARGELY ON TRACK THIS MORNING, WITH NO MAJOR UPDATES
NEEDED. THE REMAINDER OF THE PREVIOUS FORECAST FOLLOWS BELOW,
WITH UPDATES MADE TO THE AVIATION SECTION. 14
RAIN WILL CONTINUE ALL DAY, WITH THE HIGHER QPF FOCUSED IN THE
CASCADES AND COASTAL REGIONS. 2-3 INCHES ARE LIKELY IN THE
CASCADES, WITH 1-3 ALONG THE COAST AND WINDWARD SIDE OF THE
OLYMPICS. SNOW LEVELS WILL GENERALLY REMAIN HIGH THROUGHOUT MUCH
OF THE DAY, BUT BY THE AFTERNOON AND EVENING, THEY WILL START
DECREASING. ALONG WITH ANTICIPATED CONVERGENCE ZONE ACTIVITY
TONIGHT, ENOUGH SNOW FOR A WINTER WEATHER ADVISORY IS STILL ON
TRACK FOR THE STEVENS PASS AREA, WITH HIGHER AMOUNTS IN THE
CASCADES NORTH OF THE PASS AND IN THROUGH THE MOUNT BAKER AREA.
SNOWFALL TOTALS ALONG STEVENS PASS ARE LIKELY TO BE BETWEEN 5 TO
10 INCHES, WITH PERIODS OF SNOWFALL RATES THAT COULD ACHIEVE AT
LEAST ONE INCH PER HOUR TONIGHT. BREEZY CONDITIONS WITH WIND
GUSTS OF 30 TO 35 MPH OVER THE CASCADE PASSES THIS AFTERNOON
COULD MAKE FOR CHALLENGING VISIBILITIES AND TRAVELING
CONDITIONS. WINDS WILL ALSO BE BREEZY THROUGH PUGET SOUND, THE
SOUTHWEST INTERIOR, COAST AND NORTHERN OLYMPIC PENINSULA TODAY.
THE PRECIPITATION WILL CONTINUE INTO SATURDAY, BUT WILL BRIEFLY
TAPER OFF FOR SCATTERED SHOWERS INTO THE EVENING. THE NEXT
SYSTEM WILL BE RIGHT ON ITS HEELS BY SUNDAY MORNING. HIGHS WILL
BE BACK IN THE 50S THROUGH THE WEEKEND.
HIGHER ASTRONOMICAL TIDES WILL PEAK TODAY ALONG THE PACIFIC
COAST. THE INNER COASTAL AREAS WILL SEE PEAK TIDES ON SATURDAY,
THOUGH ONLY MINOR COASTAL FLOODING WILL BE POSSIBLE. COASTAL
FLOOD ADVISORIES REMAIN IN EFFECT, WITH MINOR FLOODING MOST
LIKELY AROUND HIGH TIDE TODAY AND SATURDAY.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
RAIN ASSOCIATED WITH THE NEXT SYSTEM WILL ARRIVE SUNDAY MORNING
AND LAST INTO MONDAY. ANOTHER QUARTER TO HALF INCH OF RAIN IS
EXPECTED IN THE LOWLANDS, WITH 1-2 INCHES IN THE MOUNTAINS. THE
PRIMARY POINT OF DISCUSSION IN THE EXTENDED FORECAST WILL BE A
STRONG ATMOSPHERIC RIVER SYSTEM THAT WILL TAKE AIM AT WASHINGTON
MONDAY THROUGH AT LEAST THE MIDDLE OF THE WEEK. INDICATIONS AT
THIS TIME ARE THAT A SECOND ATMOSPHERIC RIVER WILL MOVE IN FOR
THE SECOND HALF OF THE WEEK, BUT NOT BE AS WET AS THE FIRST ONE.
DURING THIS TIME, SIGNIFICANT RAINFALL IS EXPECTED AREA WIDE,
MAKING FOR A VERY WET WEEK. TO PUT IT IN PERSPECTIVE, THE TOTAL
QPF EXPECTED BETWEEN MONDAY MORNING AND FRIDAY MORNING FOR THE
CASCADES AND OLYMPICS IS BETWEEN 7 AND 11 INCHES. AREAS FROM
SEATTLE SOUTH COULD SEE 3 TO 5 INCHES OF RAIN. WHIDBEY ISLAND
MAY BE THE MOST RAINSHADOWED LOCATION IN THE WHOLE EVENT YET
STILL RECEIVE 2-2.5 INCHES OF RAIN. SEE THE HYDROLOGY SECTION
FOR MORE INFORMATION ON AREA RIVERS.
21
AVIATION
NORTHWEST FLOW ALOFT WILL CONTINUE THROUGH TODAY AS A FRONTAL
SYSTEM MOVES ACROSS WESTERN WASHINGTON. WIDESPREAD LIFR/IFR
CONDITIONS CONTINUE THIS MORNING WITH A WARM FRONT DRAPED OVER
THE REGION AND WITH SUBSTANTIAL LOW LEVEL MOISTURE IN THE AREA.
LIFR/IFR CIGS WILL CONTINUE FOR MOST AREAS THROUGH THE REMAINDER
OF THE MORNING, WITH SLOW IMPROVEMENTS TO MVFR/IFR EXPECTED
THIS AFTERNOON. VSBYS WILL ALSO REMAIN LOWER THIS MORNING,
RANGING 2 TO 4 STATUTE MILES FOR MOST AREAS. STRATIFORM RAIN
THIS MORNING WILL BECOME MORE SHOWERY THIS AFTERNOON AFTER A
COLD FRONT MOVES THROUGH THE AREA. A CONVERGENCE ZONE IS
EXPECTED TO DEVELOP AROUND SNOHOMISH COUNTY THIS AFTERNOON INTO
THIS EVENING, WITH ADDITIONAL POST-FRONTAL SHOWERS EXPECTED
TONIGHT. LOCALIZED IMPROVEMENTS TO VFR WILL BE POSSIBLE THIS
EVENING IN A POST-FRONTAL AIRMASS. S/SW SURFACE WINDS WILL
INCREASE THIS MORNING, PEAKING TONIGHT. GUSTS WILL RANGE 20 TO
30 KTS FOR MOST AREAS, WITH LOCALIZED GUSTS OF 35 KTS AS WELL.
KSEA...
LIFR CONDITIONS CONTINUE AT THE TERMINAL THIS MORNING. CIGS
WILL THEN LIFT INTO IFR BETWEEN 18-21Z, BEFORE LIFTING FURTHER
INTO MVFR BY LATE AFTERNOON. LIGHT RAIN WILL PERSIST AT TIMES
THIS MORNING, WITH MAINLY DRIER CONDITIONS EXPECTED THIS
AFTERNOON OUTSIDE OF DRIZZLE. A CONVERGENCE ZONE WILL DEVELOP
THIS AFTERNOON AND WILL REMAIN NORTH OF THE TERMINAL. PRIMARILY
MVFR CIGS TONIGHT, BUT SOME BRIEF IMPROVEMENTS TO VFR WILL BE
POSSIBLE. WINDS WILL INCREASE FROM THE S/SW TO 10-20 KTS THIS
MORNING AND WILL PEAK THIS EVENING THROUGH TONIGHT. GUSTS ARE
EXPECTED TO PEAK BETWEEN 30 TO 35 KTS TONIGHT.
JD/14
MARINE
A WEATHER SYSTEM WILL MOVE ACROSS THE WATERS TODAY. WINDS WILL
INCREASE THIS MORNING, AND PEAK IN INTENSITY THIS AFTERNOON
THROUGH EARLY SATURDAY MORNING. GALE FORCE WIND GUSTS ARE
EXPECTED FOR THE COASTAL WATERS AND WESTERN STRAIT OF JUAN DE
FUCA DURING THIS PERIOD. IN ADDITION, A STRONG WESTERLY PUSH
THROUGH THE STRAIT OF JUAN DE FUCA WILL OCCUR EARLY THIS
AFTERNOON AND CONTINUE TO REMAIN ELEVATED THROUGH EARLY SATURDAY
MORNING. LOCALIZED GUSTS OF 45 KTS WILL BE POSSIBLE IN THE
CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA DURING THIS PERIOD.
STRONGER SOUTHWEST WINDS ARE ALSO EXPECTED ALONG THE SOUTHERN
PORTIONS OF THE NORTHERN INLAND WATERS AND NEAR BELLINGHAM BAY,
WITH GUSTS OF 35 KTS. FOR THIS REASON, HAVE UPGRADED THE SMALL
CRAFT ADVISORY TO A GALE WARNING FOR THE NORTHERN INLAND WATERS.
SCA WEST WINDS ARE ALSO EXPECTED ALONG THE NORTHERN PERIPHERY
OF ADMIRALTY INLET, AND HAVE ISSUED A SCA FOR THIS REGION. GUSTS
MAY ALSO PEAK BRIEFLY AROUND 35 KTS FOR PUGET SOUND TONIGHT,
WITH PREDOMINANTLY SCA WINDS THIS AFTERNOON AND TONIGHT. WINDS
WILL SLOWLY SUBSIDE ON SATURDAY. ADDITIONAL WEATHER SYSTEMS ARE
EXPECTED OVER THE NEXT WEEK, THE NEXT BEING ON SUNDAY MORNING,
AND A STRONGER WEATHER SYSTEM MONDAY INTO TUESDAY. FURTHER
HEADLINES WILL LIKELY BE REQUIRED, WITH POTENTIAL GALES AGAIN
WITH THE MONDAY AND TUESDAY WEATHER SYSTEM.
SEAS OF 4 TO 7 FEET THIS MORNING WILL BUILD TO 13 TO 18 FEET TONIGHT
INTO SATURDAY MORNING. SEAS WILL THEN SUBSIDE TO 8 TO 9 FEET
SATURDAY NIGHT INTO SUNDAY. SEAS WILL BUILD AGAIN LATE MONDAY INTO
MIDWEEK WITH THE NEXT WEATHER SYSTEMS. JD
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 TODAY WILL PUT THE AREA OF GREATEST PRECIPITATION IN THE
NORTH CENTRAL WASHINGTON CASCADES. SNOW LEVELS WILL INITIALLY
RANGE 6500 TO 8000 FEET TODAY BEFORE FALLING TO 4000 FEET
TONIGHT AND SATURDAY.
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 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). ADDITIONAL
PRECIPITATION IS ALSO POSSIBLE THURSDAY INTO FRIDAY WITH CONTINUED
WESTERLY FLOW ALOFT.
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.
JD/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 THIS EVENING TO 10 PM PST
SATURDAY FOR CASCADES OF SNOHOMISH AND NORTHERN KING
COUNTIES.
COASTAL FLOOD ADVISORY UNTIL 3 PM PST THIS AFTERNOON 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.
WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM PST SATURDAY
FOR ISLAND COUNTY.
PZ...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 PM PST
SATURDAY FOR GRAYS HARBOR BAR.
GALE WARNING FROM 1 PM THIS AFTERNOON TO 4 AM PST SATURDAY FOR
WEST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 4 AM TO 10 PM 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-WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING FROM 1 PM THIS AFTERNOON TO 10 AM PST SATURDAY
FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA-NORTHERN
INLAND WATERS INCLUDING THE SAN JUAN ISLANDS.
SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM PST
SATURDAY FOR ADMIRALTY INLET.
SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 4 AM PST
SATURDAY FOR PUGET SOUND AND HOOD CANAL.
GALE WARNING UNTIL 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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