428
FXUS66 KPQR 121835 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1035 AM PST WED NOV 12 2025
UPDATED AVIATION DISCUSSION AND HAZARDS.
SYNOPSIS
RELATIVELY CALM WEATHER CONDITIONS CONTINUES THIS
MORNING AHEAD OF THE NEXT SYSTEM. COULD SEE SOME LIGHT SHOWERS
THIS AFTERNOON, BUT MOST PLACES REMAIN DRY. TONIGHT, A COLD
FRONT WILL PUSH THROUGH THE AREA, RETURNING WIDESPREAD RAIN.
SNOW LEVELS FALL THURSDAY INTO EARLY FRIDAY, RETURNING CHANCES
FOR ACCUMULATING, SUB-ADVISORY SNOW ACROSS THE CASCADE PASSES.
THE ACTIVE AND UNSETTLED PATTERN IS EXPECTED TO PERSIST THROUGH
THE WEEKEND AND INTO EARLY NEXT WEEK.
DISCUSSION...NOW THROUGH TUESDAY
SATELLITE IMAGERY AS OF
EARLY WEDNESDAY MORNING DEPICTS MID TO HIGH LEVEL CLOUD COVER
ACROSS THE REGION AHEAD OF THE NEXT SYSTEM. THERE IS DENSE FOG
BEING OBSERVED IN THE SOUTHERN WILLAMETTE VALLEY THIS MORNING
BASED ON WEBCAMS AND OBSERVATIONS AT THE KEUG (EUGENE) ASOS.
THEREFORE, A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE LANE
COUNTY LOWLANDS UNTIL 10 AM THIS MORNING. PATCHY DENSE FOG IS
POSSIBLE ACROSS OTHER CENTRAL/SOUTHERN WILLAMETTE VALLEY
LOCATIONS INCLUDING CORVALLIS AND ALBANY. IF YOU'LL BE COMMUTING
IN THE FOG THIS MORNING, MAKE SURE TO SLOW DOWN, USE LOW BEAM
HEADLIGHTS, AND LEAVE PLENTY OF DISTANCE AHEAD OF YOU. ANY FOG
THIS MORNING SHOULD LIFT BY 10-11 AM AS MIXING INCREASES DUE TO
DAYTIME HEATING AND THE INCOMING SYSTEM.
WEATHER SHOULD REMAIN BENIGN THIS MORNING AHEAD OF THE NEXT
SYSTEM. THIS AFTERNOON, A WEAK WARM FRONT ASSOCIATED WITH A LOW
PRESSURE SYSTEM IN THE NE PACIFIC WILL LIFT OVER NORTHWEST
OREGON AND SOUTHWEST WASHINGTON. THIS COULD POTENTIALLY BRING
LIGHT SHOWERS TO THE COAST AS BY 10 AM-1 PM WED AND ACROSS THE
WILLAMETTE VALLEY BY 1-2 PM WED. GIVEN WE'VE BEEN DRY THE LAST
FEW DAYS, IT MAY TAKE SOME TIME FOR THE ATMOSPHERE TO SATURATE;
THUS, MANY PLACES COULD STAY DRY THIS AFTERNOON. REFS GUIDANCE
SUGGESTS ONLY A 5-15% CHANCE FOR MEASURABLE RAIN (>0.01") FOR
COASTAL LOCATIONS SOUTH OF TILLAMOOK AND INLAND LOCATIONS SOUTH
AND EAST OF LONGVIEW FROM 12-6 PM TODAY. THE HIGHEST CHANCES
(20-30%) ARE ALONG THE NORTH OREGON AND SOUTH WASHINGTON COASTS.
AT THE VERY LEAST, WE'LL DEFINITELY BE OVERCAST TODAY. WINDS
ARE ALSO NOT A CONCERN TODAY AS THERE IS A LESS THAN 5% CHANCE
FOR WIND GUSTS GREATER THAN 35 MPH ACROSS THE AREA.
TONIGHT, THE AFOREMENTIONED LOW PRESSURE SYSTEM WILL STRENGTHEN
AND SWING A COLD FRONT THROUGH THE REGION, RETURNING WIDESPREAD
RAIN. THE MAJORITY OF ENSEMBLE MEMBERS FROM THE
GFS/EURO/CANADIAN ARE IN AGREEMENT THAT THE CENTER OF THE LOW
WILL BE STRONGEST JUST OFFSHORE OF SOUTHERN OREGON AND NORTHERN
CALIFORNIA, SO THOSE AREAS ARE FAVORED TO RECEIVE THE HEAVIEST
PRECIPITATION. FOR OUR AREA BETWEEN 10 PM WEDNESDAY AND 10 PM
THURSDAY, CHANCES FOR 24-HOUR RAINFALL EXCEEDING 0.50 INCH ARE
AROUND 30-50% FOR INTERIOR VALLEYS (HIGHEST CHANCES ACROSS THE
SOUTHWEST WASHINGTON LOWLANDS), AND 60-80% ALONG THE COAST,
COAST RANGE, WILLAPA HILLS, AND NORTH OREGON/SOUTH WASHINGTON
CASCADES. WINDS WILL ALSO INCREASE AND TURN MORE SOUTHWESTERLY
ON THURSDAY, BUT LIKELY (80% CHANCE) REMAIN NON-IMPACTFUL. THERE
IS ONLY A 10-20% CHANCE FOR IMPACTFUL WIND GUSTS EXCEEDING 45
MPH ALONG THE COAST, AND A 5-10% CHANCE FOR INLAND LOCATIONS.
THIS SCENARIO WOULD ONLY OCCUR IF THE LOW ENDS UP STRENGTHENING
AND TRACKING FURTHER NORTH (OFFSHORE OF CENTRAL/NORTHERN
OREGON).
SINCE THE LOW IS EXPECTED TO TRACK FURTHER SOUTH, TEMPERATURES
HAVE TRENDED WARMER ACROSS THE REGION BEHIND THE COLD FRONT,
INCLUDING THE CASCADES. CHANCES FOR SNOW LEVELS DROPPING BELOW
5000 FT (PASS-LEVEL) THURSDAY-FRIDAY ARE NOW 25-45% ACROSS THE
OREGON CASCADES, WITH THE HIGHEST CHANCES (45%) AT HIGHWAY 26
NEAR GOVERNMENT CAMP, AND LOWEST CHANCES (25-35%) AT SANTIAM AND
WILLAMETTE PASSES. CHANCES FOR 48-HOUR SNOWFALL OF 6 INCHES OR
GREATER (ADVISORY LEVEL) BETWEEN 4 AM THURSDAY AND 4 AM
SATURDAY HAVE NOW FALLEN TO 5-10% ACROSS THESE PASSES. FOR ONE
INCH OF SNOW IN THE PASSES, THE CHANCES ARE 30-40%. ANOTHER
CHANGE THESE RELATIVELY WARMER TEMPERATURES HAVE ARE ON
THUNDERSTORM POTENTIAL. SINCE WE WON'T BE AS COOL ALOFT,
INSTABILITY IS MORE LIMITED AND THUS CHANCES FOR THUNDERSTORMS
THURSDAY HAVE FALLEN TO 10% OR LESS ACROSS NORTHWEST OREGON AND
SOUTHWEST WASHINGTON.
THE BROADER WEATHER PATTERN STAYS ACTIVE THROUGH THE END OF THE
WEEKEND AND INTO THE WEEKEND. A WARM FRONT LIFTING NORTH ON
SATURDAY WILL RAISE SNOW LEVELS AND TRANSITION PRECIPITATION
BACK TO RAIN IN THE CASCADES, FOLLOWED BY ANOTHER COLD FRONT ON
SUNDAY THAT WILL LOWER SNOW LEVELS ONCE AGAIN, RETURNING SNOW
CHANCES TO THE PASSES BY SUNDAY NIGHT. ELSEWHERE, PERIODIC RAIN
IS EXPECTED TO PERSIST THROUGH TUESDAY UNDER CONTINUED SOUTHWEST
FLOW ALOFT. -10
AVIATION
LOW STRATUS AND FOG CONTINUE TO BLANKET THE CENTRAL
AND SOUTHERN WILLAMETTE VALLEY AS WELL AS MUCH OF THE COAST AT 18Z
WED. MVFR/IFR CIGS AND VIS ARE EXPECTED TO IMPROVE TO VFR
CONDITIONS BY 20-22Z WED FOR INLAND LOCATIONS AND BY 00Z FOR
COASTAL LOCATIONS AS A WARM FRONT LIFTS NORTHWARD THROUGH THE
REGION, BRINGING MIXING TO THE REGION ALONG WITH SCATTERED -SHRA
OR -DZ. WINDS GENERALLY LIGHT AND VARIABLE ACROSS THE REGION FOR
MOST OF THE TAF PERIOD, EXCEPT FOR BRIEF SOUTHERLY WINDS ALONG THE
COAST FROM 18Z WED-00Z THU WITH GUSTS UP TO 20 KT AT KONP AS THE
FRONT PASSES THROUGH. ALSO, EAST WINDS ARE GUSTY THROUGH THE
COLUMBIA RIVER GORGE, BRINGING GUSTS UP TO 20-25 KTS AT KTTD
THROUGH 00Z THU.
KPDX AND APPROACHES...VFR WITH LIGHT AND VARIABLE WINDS UNDER 5 KT
EXPECTED THROUGH THE PERIOD. RAIN SHOWERS BEGIN AFTER 21Z WED-00Z
THU. -03
MARINE
HIGH PRESSURE OVER THE WATERS WILL MAINTAIN CALM
MARINE CONDITIONS THROUGH EARLY THIS MORNING. WINDS WILL
GENERALLY REMAIN EAST SOUTHEASTERLY WITH GUSTS LESS THAN 15 KT
AND SEAS OF 7-8 FT AT 13-14 SEC. THE NEXT LOW PRESSURE SYSTEM IN
THE NE PACIFIC WILL RETURN BREEZY SOUTHERLY WINDS AND BUILDING
SEAS TODAY, WITH HIGH CONFIDENCE FOR ANOTHER PERIOD OF
CONDITIONS HAZARDOUS TO SMALL CRAFT. AS THIS SYSTEM SWINGS A
FRONT THROUGH THE WATERS, THERE'S A 60-80% CHANCE OF FREQUENT
SOUTHERLY WIND GUSTS EXCEEDING 21 KT THIS AFTERNOON AND A
GREATER THAN 90% CHANCE THAT SEAS BUILD ABOVE 10 FT BY LATE
WEDNESDAY NIGHT/EARLY THURSDAY MORNING.
WINDS BRIEFLY TURN EASTERLY AND EASE TO AROUND 20 KT OR LESS
WEDNESDAY NIGHT, HOWEVER, WINDS QUICKLY INCREASE AND TURN
SOUTHERLY AGAIN ON THURSDAY AS THE LOW DEEPENS AND SWINGS
ANOTHER FRONT THROUGH THE WATERS. WILL NOTE THAT OCCASIONAL
GALE-FORCE WIND GUSTS OF 34 KT OR GREATER ARE POSSIBLE BETWEEN
10 AM AND 4 PM THURSDAY, MAINLY SOUTH OF CAPE FALCON AND BEYOND
20-30 NM. THIS AREA WILL ALSO HAVE A 40-50% CHANCE FOR SEAS
BUILDING ABOVE 15 FT. THE SMALL CRAFT ADVISORY FOR ALL MARINE
ZONES GOES INTO EFFECT 10 AM WEDNESDAY AND HAS BEEN EXTENDED
THROUGH 4 AM FRIDAY.
ANOTHER FRONTAL SYSTEM WILL SWING THROUGH BRITISH COLUMBIA AND
FAR NORTHWEST WASHINGTON ON FRIDAY, MAINTAINING RELATIVE
BREEZY SOUTHWESTERLY WINDS OVER OUR COASTAL WATERS. HOWEVER,
CHANCES FOR FREQUENT WIND GUSTS STRONGER THAN 21 KT ARE ONLY
AROUND 30-40% ON FRIDAY. -10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 4 AM PST FRIDAY FOR
PZZ210-251>253- 271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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