159
FXUS66 KPQR 220501
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1001 PM PDT WED OCT 21 2026
UPDATED AVIATION DISCUSSION AND WATCHES/WARNINGS/ADVISORIES SECTION.
SYNOPSIS
DRY AND COOLING TEMPERATURES WILL OCCUR THROUGH
THE WORK WEEK BEFORE WEAK STORM SYSTEMS RETURN CHANCES FOR
BENEFICIAL RAIN OVER THE WEEKEND AND EARLY NEXT WEEK.
DISCUSSION...NOW THROUGH TUESDAY
ENSEMBLES ARE IN GOOD
AGREEMENT SHORTWAVE RIDGING WILL GIVE WAY TO A WEAK SHORTWAVE
TROUGH TRAVERSING THE REGION THURSDAY. SOME MOISTURE AND WEAK
INSTABILITY WILL RESULT IN A 20-30% CHANCE FOR LIGHT SHOWERS
ACROSS THE CASCADES THURSDAY AFTERNOON AND EVENING.
A WEAK FRONT, CURRENTLY WELL OFFSHORE, IS CURRENTLY ASSOCIATED
WITH THE SHORTWAVE TROUGH, BUT MODELS ARE IN GOOD AGREEMENT IT
WILL DISSIPATE BEFORE REACHING OUR FORECAST AREA, AND THUS HAVE
FEW IMPACTS ASIDE FROM BRINGING AN INCREASE IN CLOUD COVER AND
COOLER TEMPERATURES TO THE REGION. ON THAT NOTE, MODELS
GENERALLY AGREE SKIES WILL CLEAR THURSDAY AND FRIDAY NIGHTS AWAY
FROM THE CASCADES IN THE WILLAMETTE VALLEY, WHICH WILL ALLOW
TEMPERATURES TO DROP TO SOME OF THE COLDEST VALUES SO FAR THIS
YEAR. IT APPEARS INCREASINGLY LIKELY WE WILL NEED A FREEZE WATCH
FOR AT LEAST THE SOUTHERN WILLAMETTE VALLEY AND COAST RANGE
VALLEYS WITH A MORE EXPANSIVE THREAT OF A FREEZE ON FRIDAY NIGHT
PER NBM PROBABILITIES.
THE NEXT SHORTWAVE TROUGH OR CUTOFF LOW IS FORECAST TO DROP
TOWARDS THE PACIFIC NORTHWEST OVER THE WEEKEND INTO EARLY NEXT
WEEK. THERE REMAINS QUITE A BIT OF UNCERTAINTY AROUND WHETHER
OR NOT THIS STORM SYSTEM WILL CUTOFF, CLIP THE REGION AND THEN
HANG WELL OFFSHORE FOR 24-48 HOURS BEFORE PUSHING INLAND, HOVER
OVER OR CLOSE ENOUGH TO THE REGION TO BRING A COUPLE BOUTS OF
RAIN OVER 48-72 HOURS, OR IF THE ENTIRE STORM SYSTEM WILL
REMAIN AN OPEN SHORTWAVE TROUGH THAT SLIDES SOUTHEASTWARD ACROSS
THE ROCKIES AND KEEPS THE AREA LARGELY DRY.
AVIATION...THROUGH 06Z THURSDAY
HIGH PRESSURE OVER THE REGION
WILL LEAD TO PREDOMINANTLY LIGHT WINDS AND VFR CONDITIONS THROUGH
THE TAF PERIOD. THE MAIN EXCEPTION TO THIS WILL BE BETWEEN 09-18Z
THURSDAY WHEN CLEAR SKIES, LIGHT WINDS, AND LOW LEVEL MOISTURE WILL
LEAD TO POCKETS OF FOG AND LOW CLOUDS DEVELOPING IN INLAND VALLEYS.
THE HIGHEST PROBABILITIES FOR IFR CONDITIONS DEVELOPING AT TAF SITES
ARE AT KEUG BETWEEN 09-18Z THURSDAY WHERE THERE IS A 30-40% CHANCE
FOR THESE CONDITIONS OCCURRING AT ANY GIVEN HOUR DURING THAT
TIMEFRAME. THERE IS AROUND A 15-25% CHANCE OF MVFR/IFR CONDITIONS
DEVELOPING AT ANY GIVEN HOUR AT ANY OTHER INLAND TERMINAL DURING
THIS TIME PERIOD. IN ADDITION, IFR CONDITIONS WERE OBSERVED AT KONP
AT 04Z THU, AND THERE'S A 50-60% CHANCE OF MVFR/IFR CONDITIONS
CONTINUING THROUGH 15-19Z THU.
WINDS WILL BE LIGHT AND VARIABLE INTO THE MORNING HOURS. THEN A WEAK
FRONT WILL TURN WINDS NORTHWESTERLY AND INCREASE AFTER 18Z THU ALONG
THE COAST TO 12-15 KTS WITH GUSTS UP TO 25 KTS AND AFTER 20-22Z
INLAND TO 8-12 KTS.
KPDX AND APPROACHES...HIGH PRESSURE OVER THE REGION WILL LEAD TO
LIGHT WINDS AND PREDOMINANTLY VFR CONDITIONS. THE MAIN EXCEPTION TO
THIS WILL BE IN THE 11-18Z THURSDAY TIME PERIOD WHEN THERE IS A 20-
30% CHANCE FOR MVFR/IFR CONDITIONS DEVELOPING AT ANY GIVEN HOUR.
WINDS LIGHT AND VARIABLE BECOMING NORTHWEST 8-10 KTS AFTER 20-22Z
THU. -03
MARINE
NORTH WINDS WILL DEVELOP ACROSS THE WATERS THIS EVENING
AND PERSIST THROUGH AT LEAST SATURDAY. THE WINDS STRENGTHEN
TONIGHT AND THURSDAY AS HIGH PRESSURE BUILDS IN THE WAKE OF A
WEAK FRONT WITH HIGH CONFIDENCE IN SMALL CRAFT CONDITIONS. THE
PERSISTENT WINDS WILL INCREASE SEAS. THE SEAS ARE EXPECTED TO
BECOME VERY STEEP THURSDAY NIGHT AND FRIDAY PROMPTING A HAZARDOUS
SEAS WARNING.
A STRONGER LOW WILL APPROACH THE WATERS FRIDAY. MODEL ENSEMBLES
HAVE BEEN TRENDING TOWARDS THE LOW REMAINING FURTHER OFFSHORE THIS
WEEKEND. THERE IS UNCERTAINTY ON WHEN AND IF THE LOW WILL MOVE
CLOSER TO SHORE AND A DIMINISHING THREAT OF GALE CONDITIONS THIS
WEEKEND. ~11
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY FROM 11 PM FRIDAY TO 9 AM PDT SATURDAY FOR
ORZ101>103-105-107>109-111>113-119-123.
FREEZE WATCH FROM THURSDAY EVENING THROUGH FRIDAY MORNING FOR
ORZ104-116>118.
FREEZE WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR
ORZ104-106-114>118-124-125.
FROST ADVISORY FROM 11 PM THURSDAY TO 9 AM PDT FRIDAY FOR
ORZ105>107-109-114-115-124-125.
WA...FROST ADVISORY FROM 11 PM FRIDAY TO 9 AM PDT SATURDAY FOR
WAZ203>208.
FROST ADVISORY FROM 11 PM THURSDAY TO 9 AM PDT FRIDAY FOR
WAZ203>205-208.
PZ...SMALL CRAFT ADVISORY FROM 11 AM THURSDAY TO 8 AM PDT FRIDAY FOR
PZZ210.
SMALL CRAFT ADVISORY FROM 5 AM TO 8 PM PDT THURSDAY FOR PZZ251-
271-272.
HAZARDOUS SEAS WARNING FROM 8 PM THURSDAY TO 8 AM PDT FRIDAY
FOR PZZ251>253-271>273.
SMALL CRAFT ADVISORY FROM 11 AM TO 8 PM PDT THURSDAY FOR PZZ252-
253-273.
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