255
FXUS66 KPQR 030942
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
242 AM PDT SAT OCT 3 2026
SYNOPSIS
WARMING TREND CONTINUES THROUGH THE WEEKEND AS HIGH
PRESSURE PEAKS ON SUNDAY, WITH PERIODS OF OFFSHORE FLOW AND
EARLY MORNING FOG WITHIN SHELTERED VALLEYS. TEMPERATURES
MODERATE BUT REMAIN ABOVE NORMAL AS DRY WEATHER PERSISTS
THROUGH MUCH OF THE WORKWEEK. MORE SEASONABLE CONDITIONS WITH
INCREASED CHANCES FOR RAIN MAY RETURN LATE IN THE WEEK.
SHORT TERM...NOW THROUGH SUNDAY NIGHT
UPPER-LEVEL RIDGING
CENTERED OVER THE DESERT SOUTHWEST WILL AMPLIFY THROUGH THE
WEEKEND BEHIND A PASSING SHORTWAVE TRACKING TOWARD THE GREAT
LAKES. LOCALLY, THE RIDGE AXIS WILL REMAIN OVERHEAD TODAY BEFORE
SHIFTING INLAND ON SUNDAY, WHILE A WEAK THERMAL TROUGH ALONG
THE COAST WILL SET UP AN OFFSHORE PRESSURE GRADIENT FAVORING
NOCTURNAL EAST WINDS WITHIN TERRAIN. SHORT- RANGE ENSEMBLES
CONTINUE TO SUPPORT A GRADIENT OF -1 TO -3 MB BETWEEN PORTLAND
AND THE DALLES WITH ONLY A FEW MEMBERS SUPPORTING A GRADIENT AS
HIGH AS -4 MB ON SUNDAY MORNING. THIS MAGNITUDE OF GRADIENT
FAVORS A DIURNALLY VARYING WIND WITH OFFSHORE (EASTERLY) FLOW
DEVELOPING NIGHTLY OVER THE CASCADES AND THEIR WESTERN SLOPES,
AS WELL AS POSSIBLY THE HIGHEST REACHES OF THE COAST RANGE,
BEFORE DAYTIME MIXING SEES WINDS DECREASE OVER TERRAIN AND
INCREASE OUT OF THE NORTH WITHIN INLAND VALLEYS. THESE OFFSHORE
WINDS WILL PEAK TONIGHT INTO SUNDAY MORNING, WITH GUSTS OF 20-30
MPH IN THE CASCADES AND FOOTHILLS, HIGHEST IN TYPICALLY WINDS
AREAS WITHIN AND NEAR THE COLUMBIA RIVER GORGE.
AS RIDGING PEAKS OVERHEAD THIS WEEKEND, MID-LEVEL TEMPERATURES
WILL RISE TO AROUND 20C, YIELDING HIGH TEMPERATURES AT THE
SURFACE SOME 10-15 DEGREES ABOVE NORMAL IN THE LOW TO MID 80S
ON SUNDAY. SUFFICIENTLY COOL OVERNIGHT TEMPERATURES WILL ALLOW
MOST OF THE REGION TO MAINTAIN ONLY MINOR HEATRISK, BUT OFFSHORE
WINDS ELEVATING OVERNIGHT TEMPERATURES WITHIN CASCADE VALLEYS
AND THE COLUMBIA GORGE WILL SUPPORT LOCAL POCKETS OF MODERATE
HEATRISK IN THOSE AREAS ON SUNDAY. OTHERWISE, CHANCES FOR
MODERATE HEATRISK PEAK AT 20-30% IN THE PORTLAND-VANCOUVER METRO
AREA, GENERALLY CORRESPONDING TO THE CHANCE OF SUNDAY MORNING
LOWS FALLING ONLY TO THE UPPER 50S. MOST AREAS ARE NOT EXPECTED
TO REACH DAILY RECORD HIGHS (UPPER 80S TO LOW 90S AT INLAND
SITES), EXCEPT A RELATIVELY LOW RECORD OF 84F AT PORTLAND INT'L
SET IN 1952 MAY BE MOST AT RISK OF BEING TIED OR BROKEN.
THIS PATTERN WILL ADDITIONALLY PROMOTE NIGHTLY AREAS OF VALLEY
FOG THANKS TO LIGHT WINDS AWAY FROM THE CASCADES, DRY MID AND
UPPER LEVELS LIMITING CLOUD COVER, AND ROBUST NOCTURNAL
INVERSIONS DURING INCREASINGLY LONG NIGHTS. COAST RANGE VALLEYS
WILL CONTINUE TO BE THE MOST LIKELY TO SEE AREAS OF LIMITED
VISIBILITY, WITH THE COVERAGE OF POTENTIAL FOG WITHIN THE
WILLAMETTE VALLEY BEING PARTICULARLY UNCERTAIN. WHERE FOG DOES
FORM, IF COULD EASILY BECOME DENSE AS RIDGING ALOFT COMPRESSES
THE SURFACE LAYER BENEATH THE NOCTURNAL INVERSION. IN A SIMILAR
STRAIN, A SHALLOW BUT SATURATED MARINE LAYER MAY EASILY RESULT
IN NIGHTLY DENSE FOG WITHIN COASTAL COMMUNITIES BEFORE MIXING
OUT THROUGH THE MORNING. DENSE FOG ADVISORIES REMAIN IN PLACE
THROUGH 10 AM PDT SATURDAY ALONG THE CENTRAL AND NORTH OREGON
AND SOUTH WASHINGTON COASTS WHERE OBSERVATIONS AND AVAILABLE
CAMERAS DEPICT WIDESPREAD FOG COVERAGE EARLY THIS MORNING.
ADDITIONAL DENSE FOG ADVISORIES MAY BE NEEDED EARLY SUNDAY. -36
LONG TERM...MONDAY THROUGH FRIDAY
BY THE BEGINNING OF THE
WORKWEEK, THERE REMAINS GOOD AGREEMENT THAT THE UPPER-LEVEL
RIDGE WILL SHIFT INLAND OVER THE ROCKIES WHILE ITS AMPLITUDE
DECREASES, RESULTING IN NEARLY ZONAL FLOW OVER THE PACIFIC
NORTHWEST. THIS PATTERN SHIFT WILL ALLOW ONSHORE FLOW TO RETURN,
SUPPORTING MODERATING BUT STILL ABOVE NORMAL TEMPERATURES
MONDAY THROUGH THURSDAY. THE BROAD RIDGE CONTINUES TO SUPPORT
HIGH CONFIDENCE IN FURTHER DRY WEATHER. LATE IN THE WEEK, THERE
IS INCREASING AGREEMENT THAT UPPER TROUGHING WILL RETURN TO THE
GULF OF ALASKA, BRINGING RENEWED RAIN CHANCES TO THE REGION FROM
FRIDAY INTO THE WEEKEND. WHILE DETAILS IN TIMING AND AMOUNTS
REMAIN LOW CONFIDENCE, SOME 60% OF LONG-RANGE ENSEMBLE MEMBERS
FAVOR RAIN AT SOME POINT FROM FRIDAY THROUGH THE WEEKEND. -36
AVIATION...THROUGH 06Z SUNDAY
SATELLITE IMAGERY AND TERMINAL
OBSERVATIONS AS OF LATE FRIDAY EVENING DEPICTS LOW MARINE
STRATUS ALONG THE COAST BRINGING LIFR CIGS AND IFR/LIFR VIS TO
KAST AND KONP. HIGH CONFIDENCE THAT THESE TRENDS CONTINUE
THROUGH 16-17Z SAT WITH 1/2SM FOG AT KONP. HIGH PRESSURE ALOFT
IS BUILDING, WHICH IS RESULTING IN THE MARINE LAYER BEING PUSHED
LOWER TO THE SURFACE. FOR WILLAMETTE VALLEY TERMINALS, VFR
CONDITIONS PREVAIL THROUGH THE TAF PERIOD WITH HIGH CLOUDS.
THERE IS A 15-30% CHANCE FOR MVFR STRATUS AT ANY GIVEN HOUR
BETWEEN 10-17Z SAT, BUT DUE TO LOW CONFIDENCE, MVFR CONDITIONS
WERE NOT INCLUDED IN THE TAFS. NORTHERLY TO NORTHWESTERLY WINDS
ACROSS THE REGION GENERALLY UNDER 10 KT. EASTERLY WINDS INCREASE
THROUGH THE COLUMBIA RIVER GORGE AND FAR EAST PORTLAND METRO
(KTTD), BUT REMAIN LIGHT.
KPDX AND APPROACHES...VFR WITH HIGH CLOUDS THROUGH THE TAF
PERIOD. 10-20% CHANCE FOR MVFR STRATUS AT ANY GIVEN HOUR
BETWEEN 11-16Z SAT. NORTHWESTERLY WINDS 2-6 KT. -10
MARINE
PERSISTENT HIGH PRESSURE OFFSHORE WILL SEE NORTHERLY
WINDS PREVAIL THROUGH MUCH OF THE NEXT WEEK, WITH SPEEDS
REACHING DIURNAL PEAKS EACH AFTERNOON. CHANCES FOR PEAK WIND
GUSTS OF 20-25 KT GENERALLY INCREASE DAILY THROUGH WEDNESDAY,
THOUGH THE DURATION AND COVERAGE STRONGER GUSTS MAY NOT BE
SUFFICIENT TO SUPPORT SMALL CRAFT ADVISORIES EACH DAY. HIGH
PRESSURE BUILDING ALOFT THROUGH THIS WEEKEND WILL ALSO SUPPORT
AREAS OF DENSE FOG DEVELOPING NIGHTLY AS CLOUD BASES ARE
COMPRESSED DOWN TO THE SURFACE. A DENSE FOG ADVISORY THEREFORE
REMAINS IN EFFECT THROUGH NOON SATURDAY FOR WIDESPREAD
VISIBILITY OF 1 SM OR LESS, ESPECIALLY WITHIN 40 NM OF THE
COAST. STRENGTHENING NORTHERLY FLOW WILL SEE LARGELY WIND-
DRIVEN SEAS CONTINUE AT 4-6 FT THROUGH MUCH OF THE WEEK, WITH A
MODEST WEST-NORTHWEST SWELL AT 8-9 SECONDS LENGTHENING TO 10-12
SECONDS EARLY IN THE WORKWEEK.
MORE ACTIVE MARINE CONDITIONS ARE LIKELY IN THE LATTER HALF OF
THE WEEK AS TROUGHING OVER THE GULF OF ALASKA GENERATES A
BUILDING NORTHWEST SWELL AND CHANCES FOR RAIN RETURN TO THE
REGION FRIDAY INTO NEXT WEEKEND. -36
PQR WATCHES/WARNINGS/ADVISORIES
OR...DENSE FOG ADVISORY UNTIL 10 AM PDT THIS MORNING FOR ORZ101>103.
WA...DENSE FOG ADVISORY UNTIL 10 AM PDT THIS MORNING FOR WAZ201.
PZ...DENSE FOG ADVISORY UNTIL NOON PDT TODAY 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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