935
FXUS66 KSEW 050923
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
123 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 IS MOVING IN FROM THE NORTHWEST EARLY THIS MORNING, WITH
THE MORE MODERATE RAIN NOW INTO THE SOUTHERN CASCADES. 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 EARLY THIS MORNING WITH A WARM FRONT DRAPED OVER THE
OLYMPIC PENINSULA AND SUBSTANTIAL LOW LEVEL MOISTURE. LIFR/IFR
CIGS WILL CONTINUE FOR MOST AREAS THROUGH THIS MORNING, WITH
SLOW IMPROVEMENTS TO MVFR/IFR 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 TONIGHT. LOCALIZED IMPROVEMENTS TO VFR 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 TO CONTINUE THROUGH THIS MORNING, WITH BRIEF
IMPROVEMENTS TO LOW-END IFR POSSIBLE. CIGS WILL THEN LIFT INTO IFR
BETWEEN 18-21Z, BEFORE LIFTING FURTHER INTO MVFR LATE AFTERNOON.
RAIN AT TIMES THIS MORNING, WITH MAINLY DRIER CONDITIONS THIS
AFTERNOON, OTHER THAN LINGERING SHOWERS OR DRIZZLE. A CONVERGENCE
ZONE WILL DEVELOP THIS AFTERNOON AND REMAIN NORTH OF THE TERMINAL.
PRIMARILY MVFR CIGS TONIGHT, BUT SOME BRIEF IMPROVEMENTS TO VFR
POSSIBLE. LIGHT WINDS EARLY THIS MORNING WILL INCREASE FROM THE S/SW
LATE MORNING, AND PEAK THIS EVENING THROUGH TONIGHT. GUSTS ARE
EXPECTED TO PEAK BETWEEN 30 TO 35 KTS TONIGHT. JD
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 FROM 9 AM THIS MORNING TO 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.
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 FROM 10 AM THIS MORNING 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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