552
FXUS66 KPQR 212235 AAA
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
335 PM PDT TUE OCT 21 2025
SYNOPSIS
A WEAK RIDGE WILL BEGIN TO FLATTEN OVERNIGHT INTO
WEDNESDAY AS A LONG WAVE TROUGH MOVES OVER THE NORTHEAST
PACIFIC. THIS SHORT WAVE EXTENDS FROM A PARENT LOW IN THE GULF
OF ALASKA. WILL SEE A BAND OF PRECIPITATION ON WEDNESDAY WITH
THE HIGHEST PROBABILITY ALONG THE COAST AND IN SOUTHWEST
WASHINGTON. AS THE SYSTEM EXITS THE REGION WILL SEE A SHORT
PERIOD OF DRYING ON THURSDAY. THIS WILL BE THE LAST SUNNY FALL
DAY AS A SERIES OF FRONTAL SYSTEMS, AN ATMOSPHERIC RIVER, SNOW,
AND WIND MOVE INTO THE REGION BEGINNING LATE THURSDAY THROUGH
THE WEEKEND.
SHORT TERM...NOW THROUGH FRIDAY
THE SHORT TERM FORECAST COULD
BE DESCRIBED AS A PENDULUM AS THE DRY CONDITIONS FROM TODAY GIVE
WAY TO WET WEATHER ON WEDNESDAY, THEN DRYING AGAIN ON THURSDAY
MORNING.
THE HIGH PRESSURE THAT HAS KEPT THE SUNNY FALL WEATHER IN PLACE
WILL FLATTEN AS A LONG WAVE TROUGH MOVES OVER THE AREA. THIS
LONG WAVE TROUGH IS ASSOCIATED WITH A LOW PRESSURE SYSTEM IN THE
GULF OF ALASKA. THIS LOW IS THE FIRST OF MULTIPLE THAT WILL MOVE
OVER THE GENERAL AREA. BUT FIRST, THIS FIRST SYSTEM. WE WILL SEE
A SURGE OF COOLER AIR AND PRECIPITATION WITH THIS FRONTAL
SYSTEM. OVERALL PRECIPITATION WILL BE WIDESPREAD BUT LIGHT IN
MOST AREAS. THERE IS AROUND A 20-30% CHANCE OF ACCUMULATING
PRECIPITATION (AROUND 0.01") THROUGH MOST INLAND AREAS. HIGHER
PROBABILITY CLOSER TO 50% ALONG THE COAST AND SOUTHWEST
WASHINGTON. THE HIGHEST PRECIPITATION ACCUMULATION WOULD BE
ALONG THE COAST, COAST RANGE, AND SOUTH WASHINGTON CASCADES.
THERE, THERE IS AROUND A 10% CHANCE OF SEEING ACCUMULATION AS
HIGH AS 0.25" WITHIN 24 HRS.
DRYING WILL OCCUR ON THURSDAY BUT IT WILL BE SHORT LIVED AS THE
NEXT SYSTEM IS QUICKLY APPROACHING. LOOKING ALOFT, THERE AREA A
SERIES OF SMALL UPPER LEVEL LOWS WHICH WILL BE THE WEATHER
MAKERS OVER THE NEXT FEW DAYS. THE FIRST LOW WILL DROP SOUTHWARD
OVER THE WASHINGTON COAST ON FRIDAY. LOOKING AT ENSEMBLE MODELED
LOW CENTERS THERE IS A LOT OF VARIABILITY WITH A SPLATTERING OF
POSSIBILITIES WITH A VARIETY OF PRESSURE DEPTH. THE DEEPER THIS
LOW BECOMES THE STRONGER THE WINDS AND RAIN WILL BE. RIGHT NOW
THE OVERALL PATTERN ISN'T THE MOST ORGANIZED SO THERE REALLY IS
NO "WINNER" WHEN IT COMES TO MODEL OUTPUT. BASED ON CURRENT
TRENDS THOUGH THERE IS A STRONG SIGNAL FOR AN ATMOSPHERIC RIVER
MOVING THROUGH. THE IMPACTS FROM THE ATMOSPHERIC RIVER ARE
STRONGEST TO THE NORTH OF THE AREA BUT WE WILL STILL SEE
POTENTIALLY HEAVY RAINFALL. ALONG THE COAST THERE IS AROUND A
90% CHANCE THAT ACCUMULATION WILL BE GREATER THAN 0.9", AND A
10% CHANCE THAT RAIN WILL ACCUMULATE ABOVE 2 INCHES. THAT IS
QUITE THE RANGE AND WILL BE DEPENDENT ON WHERE THE LOW
ASSOCIATED WITH THE ATMOSPHERIC RIVER SETS UP. INLAND SITES WILL
SEE AROUND A HALF INCH OR SO LESS RAIN THAN THE COAST ASIDE FROM
THE SOUTH WASHINGTON CASCADES WHICH WILL SEE SIMILAR
ACCUMULATION TO THE COAST. FOR THE WILLAMETTE VALLEY THERE MAY
BE A BIT OF RAIN SHADOWING WHICH WILL LIMIT ACCUMULATION.
ALONG WITH RAIN WILL BE WIND. NBM MAXIMUM WINDS GUSTS WITHIN A
24 HOUR PERIOD WILL BE DESCRIBED BELOW. NOTE THAT THESE VALUES
REPRESENT THE HIGHEST WIND GUST SPEEDS WITHIN THAT 24 HOUR
PERIOD AND NOT NECESSARILY THE MOST PROLONGED AND DOMINATE
WINDS. A WEAK COASTAL JET WILL BEGIN TO FORM ON FRIDAY WHICH
WILL SPREAD INLAND. THEREFORE THE HIGH END SOLUTION (90TH
PERCENTILE) SHOWS WINDS ALONG THE BEACHES AND HEADLANDS AROUND
55-60 MPH THOUGH THE MOST LIKELY SCENARIO SHOWS GUSTS UP TO 45
MPH. THERE IS AROUND A 15-25% CHANCE OF HIGH WIND WARNING
LEVELS WINDS OF FREQUENT GUSTS OF 58 MPH OR GREATER. INLAND
THROUGH THE WILLAMETTE VALLEY WINDS WILL BE LOWER WITH THE MEAN
IN THE 30-35 MPH RANGE. -27
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
AS THE FRIDAY
SYSTEM EXITS THE AREA THE NEXT IS QUICK ON IT'S HEELS. THIS NEXT
LOW IS APPEARING MORE ROBUST AND SLIGHTLY MORE ORGANIZED OR
CLOSED BASED ON DETERMINISTIC MODELS. HOWEVER WHEN LOOKING AT
THE ENSEMBLES THERE IS MUCH MORE SPREAD IN REGARDS TO LOCATION.
IF THE LOW TAKES THE CURRENT PATH OF THE "MEAN" THEN IT WILL SET
UP IN A FAVORABLE SPOT FOR STRONG WINDS. IN ADDITION, THERE ARE
A FEW ENSEMBLES SHOWING A FAIRLY ROBUST LOW SITTING IN ONE OF
THE MORE IDEAL LOCATIONS FOR VERY STRONG WINDS. IF THIS WERE TO
OCCUR, IT WOULD BE HIGHLY FAVORED FOR WIND ADVISORY LEVEL WINDS
IN THE WILLAMETTE VALLEY (FREQUENT GUSTS OF 45-57 MPH). THE NBM
CURRENTLY SHOWS AROUND A 15-30% CHANCE OF ADVISORY LEVEL WINDS
WITH THE HIGHEST PROBABILITY WITHIN THE CENTRAL WILLAMETTE
VALLEY. HOWEVER, TO SHOW JUST HOW UNCERTAIN THE FORECAST IS, THE
10TH PERCENTILE (LOW END FORECAST) SHOWS WIND GUSTS OF 25 MPH
IN EUGENE WHILE THE 90TH PERCENTILE (HIGH END FORECAST) HAS
WINDS FORECAST AT 55 MPH. NEARLY A 30 MPH SHIFT. THEREFORE,
CONFIDENCE IN THE WIND FORECAST OVERALL IS UNCERTAIN AT THIS
TIME.
RAIN CONTINUES TO BE A THREAT ON SATURDAY WHICH ALONE MAY NOT BE
AN ISSUE BUT WHEN COMBINED WITH WIND WE COULD SEE SOME IMPACTS.
BECAUSE TREES ARE STILL FULL OF THEIR LEAVES AND ONCE THOSE GET
WET THEY WILL BE MORE SUSCEPTIBLE TO FALLING.
WHILE RAIN IS EXPECTED WEST OF THE CASCADES, THIS IS WHEN THE
SNOW MOVES IN TO THE CASCADES. THE LOW COMING IN IS COLD
WRAPPED CAUSING SNOW LEVELS TO DROP TO PASS LEVEL. THE CURRENT
DETERMINISTIC 48 HR FORECAST FOR SATURDAY INTO SUNDAY SHOWS
ANYWHERE FROM 4 TO 18 INCHES OF SNOW WITH THE HIGHEST
ACCUMULATION ALONG THE VOLCANOES. SNOW LEVELS WILL BE LOWEST ON
SUNDAY WHEN THEY FALL TO AROUND 3500 FT IN THE CENTRAL OREGON
CASCADES. WE WILL CONTINUE TO EVALUATE IF A WINTER WEATHER
ADVISORY IS NEEDED AS THE NEXT FEW DAYS PASS.
AFTER A BIT OF A CHAOTIC WEATHER WEEKEND MONDAY AND TUESDAY
APPEAR TO BE A BRIEF REPRIEVE BUT DON'T LET THAT FOOL YOU, WE
WILL STILL SEE RAIN AND THEN AN EVEN MORE ROBUST SYSTEM MIDWEEK.
-27
AVIATION
VFR CONDITIONS WITH CLEAR SKIES HAVE RETURNED ACROSS
THE REGION AS HIGH PRESSURE SITS OVER THE PACIFIC NORTHWEST.
EXPECT THIS TREND TO CONTINUE THE EVENING WITH VARIABLE WINDS UNDER
5 KT. TONIGHT INTO EARLY WEDNESDAY MORNING, WINDS WILL SHIFT MORE
SOUTHERLY AND HIGH CLOUDS WILL MOVE INTO THE AREA AHEAD OF A WEAK
FRONT APPROACHING THE REGION. CIGS WILL GRADUALLY FALL TO LOW-END
VFR THRESHOLDS ON WEDNESDAY, WITH A 40-60% CHANCE OF MVFR CIGS ALONG
THE COAST AFTER 15-18Z WED AS THE FRONT MOVES INLAND. RAIN WITH THIS
FRONT WILL BE LIGHT, SO NOT EXPECTING ANY VIS ISSUES. SOUTHERLY
WINDS ON WEDNESDAY WILL GENERALLY BE AROUND 10-15 KT WITH GUSTS UP
TO 20 KT ALONG THE COAST, AND 5-10 KT ACROSS THE WILLAMETTE VALLEY.
KPDX AND APPROACHES...VFR CONDITIONS WITH MOSTLY CLEAR SKIES THROUGH
THIS EVENING AS HIGH PRESSURE PERSISTS. NORTHWESTERLY WINDS THIS
AFTERNOON AROUND 5 KT OR LESS. TURNING SOUTHEASTERLY OVERNIGHT. -10
MARINE
A NORTHWESTERLY SWELL WILL CONTINUE TO BRING STEEP AND
HAZARDOUS SEAS THROUGH THIS EVENING. OBSERVATIONS AT BUOY 46029 AND
46050 AS OF 3 PM TUESDAY SHOW SEAS AROUND 14-18 FT AT 16-17 SECONDS.
SEAS ARE FORECAST TO PEAK THIS EVENING, AND WILL GRADUALLY SUBSIDE
TO 10-13 FT AT 15-16 SECONDS TONIGHT INTO EARLY WEDNESDAY MORNING.
THE HAZARDOUS SEAS WARNING FOR ALL WATERS INCLUDING THE COLUMBIA
RIVER BAR CONTINUES UNTIL 2 AM WEDNESDAY, FOLLOWED BY SMALL CRAFT
ADVISORIES.
WILL SEE SOME RELATIVELY CALMER MARINE CONDITIONS ON WEDNESDAY, WITH
SEAS BOTTOMING OUT AROUND 8-9 FT. COULD SEE A COAST JET WEDNESDAY
AFTERNOON WITH AN APPROACHING FRONT, BRINGING SOUTHERLY WIND GUSTS
UP TO 25 KT ACROSS THE INNER WATERS AND COLUMBIA RIVER BAR. MORE
ACTIVE WEATHER RETURNS THURSDAY THROUGH THE WEEKEND, WITH BREEZIER
SOUTHERLY WINDS AND BUILDING SEAS.
A DEEP LOW IN THE NORTHEAST PACIFIC WILL DRAG A COLD FRONT ACROSS
ALL WATERS AND WILL RESULT IN A PERIOD OF GALE FORCE SOUTHERLY WIND
GUSTS AND ISOLATED STORM FORCE WIND GUSTS STARTING THURSDAY EVENING
THROUGH AT LEAST LATE FRIDAY MORNING. PROBABILITIES FOR WIDESPREAD,
FREQUENT GALE FORCE WIND GUSTS OF AT LEAST 35 KT ARE 40-70%, WITH
THE HIGHEST CHANCES ACROSS THE INNER WATERS AND COLUMBIA RIVER BAR
DUE TO THE DEVELOPMENT OF ANOTHER COASTAL JET.
A GALE WATCH HAS BEEN ISSUED FOR THE WATERS NORTH OF CAPE
FOULWEATHER INCLUDING THE COLUMBIA RIVER BAR FROM 5 PM THURSDAY TO
11 AM FRIDAY. DECIDED NOT TO INCLUDE OUR SOUTHERN WATERS FOR NOW AS
THERE IS HIGHER CONFIDENCE FURTHER NORTH DUE TO THE POSITION OF THE
INCOMING FRONT. IF THE SYSTEM MOVES FURTHER SOUTH, THEN COULD SEE
MORE GALE FORCE GUSTS SPREADING SOUTHWARD.
PROBABILITIES FOR STORM FORCE WIND GUSTS UP TO 48 KT HAVE FALLEN TO
10% OR LESS, MAINLY FOR THE INNER WATERS. THIS SYSTEM WILL LIKELY
PUSH SEAS TOWARDS 17-19 FT, WITH A 10% CHANCE OR LESS FOR SEAS 20 FT
OR HIGHER.
SEAS ARE EXPECTED TO REMAIN ELEVATED THROUGH THE WEEKEND AS A SERIES
OF SYSTEMS APPROACH THE REGION, PARTICULARLY SATURDAY NIGHT INTO
SUNDAY. -10/42
BEACH HAZARDS
A BEACH HAZARDS STATEMENT REMAINS IN EFFECT
ACROSS THE NORTHERN/CENTRAL OREGON COAST AND SOUTH WASHINGTON COAST
THROUGH FRIDAY MORNING AS A LONG PERIOD, WEST-NORTHWESTERLY SWELL
WILL BRING A HIGH THREAT FOR SNEAKER WAVES. RAZOR CLAM DIGGERS AT
THE COAST WILL NEED TO EXERCISE CAUTION THIS WEEK. SNEAKER WAVES CAN
RUN UP SIGNIFICANTLY FARTHER ON A BEACH THAN NORMAL, INCLUDING OVER
ROCKS, LOGS, AND JETTIES. SNEAKER WAVES CAN SUDDENLY KNOCK PEOPLE
OFF OF THEIR FEET AND QUICKLY PULL THEM INTO THE OCEAN WHICH MAY
LEAD TO SERIOUS INJURY OR DROWNING. CAUTION SHOULD BE USED WHEN IN
OR NEAR THE WATER. ALWAYS KEEP AN EYE ON THE WAVES, AND BE
ESPECIALLY WATCHFUL OF CHILDREN AND PETS. REMEMBER, NEVER TURN YOUR
BACK ON THE OCEAN. -10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...HAZARDOUS SEAS WARNING UNTIL 2 AM PDT WEDNESDAY FOR PZZ210-
251>253-271>273.
SMALL CRAFT ADVISORY FROM 2 AM TO 5 PM PDT WEDNESDAY FOR PZZ210-
251>253-271>273.
GALE WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY MORNING FOR
PZZ210-251-252-271-272.
WWW.WEATHER.GOV/PORTLAND
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