184
FXUS66 KPQR 031731 AAC
AFDPQR
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PORTLAND OR
1030 AM PDT SAT OCT 3 2026
UPDATED PQR WATCHES/WARNINGS/ADVISORIES.
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.
UPDATE...SATURDAY MORNING
ASIDE FROM LOCALIZED POCKETS OF FOG
ALONG THE CENTRAL OREGON COAST THIS MORNING BETWEEN NEWPORT AND
FLORENCE, FOG HAS LIFTED ALONG THE COAST. WITH VISIBILITIES NOW ABOVE
1/4 MILE, DENSE FOG ADVISORIES HAVE BEEN ALLOWED TO EXPIRE. EXPECT
THE AFOREMENTIONED LOCALIZED POCKETS OF FOG TO LIFT BY NOON PDT
SATURDAY. -23
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 12Z SUNDAY
BROAD SUBSIDENCE ACROSS THE
AIRSPACE IS COMPRESSING THE SHALLOW MARINE LAYER AND PRODUCING
LIFR CIGS/VIS ALONG THE COAST AND LOWER COLUMBIA RIVER AS CLOUD
BASES ARE LOWERED NEARLY TO THE SURFACE. VIS OF 1SM OR LESS IS
LIKELY (70-80% CHANCE) TO PERSIST THROUGH MUCH OF THE MORNING AT
COASTAL TERMINALS, UNTIL 17-19Z SAT, BEFORE DIURNAL MIXING WILL
TEND TO CLEAR SKIES AND RETURN TO VFR VIS. LOW CLOUDS NEAR THE
COAST WILL PRESENT PERSISTENT 30-50% CHANCES FOR IFR CIGS
THROUGHOUT THE AFTERNOON ALONG THE IMMEDIATE COAST INCLUDING AT
KONP, WHILE TERMINALS EVEN A FEW MILES INLAND (KAST, KTMK) WILL
SEE MUCH LOWER CHANCES (10% OR LESS). A STAGNANT PATTERN WILL
SEE A REPEAT OF HIGH IFR/LIFR CHANCES AGAIN LATE SATURDAY.
AT INLAND TERMINALS, LARGELY CLEAR SKIES CONTINUE EARLY THIS
MORNING. AREAS OF LOW STRATUS ARE EXPECTED TO DEVELOP ALONG THE
WILLAMETTE VALLEY IN THE HOURS AROUND SUNRISE, SUPPORTING 30-50%
CHANCES FOR MVFR CIGS FROM 14-18Z SAT. AHEAD OF THE DEVELOPMENT
OF LOW CLOUDS, IDEAL CONDITIONS FOR RADIATIVE COOLING WILL ALLOW
FOR PATCHY FOG OR MIST, MOST LIKELY IN THE SOUTHERN WILLAMETTE
VALLEY INCLUDING AT KEUG, WHICH PERSISTS THROUGH THE LATE
MORNING. OTHERWISE, VFR CONDITIONS EXPECTED TO PREVAIL
THROUGHOUT THE PERIOD.
DIURNALLY VARYING WINDS EXPECTED ACROSS THE REGION. LIGHT
OFFSHORE (EASTERLY) FLOW AT COASTAL TERMINALS WILL BACK OUT OF
THE NORTHWEST AND BUILD TO AROUND 10 KT, BEFORE EASING AND
VEERING BACK OFFSHORE TONIGHT. EASTERLY FLOW AROUND 5 KT IS
ALSO FAVORED AT KTTD THROUGHOUT THE PERIOD. ELSEWHERE, LIGHT
WINDS OVERNIGHT WILL BUILD OUT OF THE NORTH TO NORTHWEST AT
AROUND 5 KT TODAY, THEN EASE AGAIN THIS EVENING.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED WHILE LOW STRATUS
DEVELOPS ALONG THE CASCADE FOOTHILLS AROUND SUNRISE, SUPPORTING
A 30% CHANCE FOR MVFR CIGS FROM 14-17Z SAT. OTHERWISE, LARGELY
CLEAR SKIES WITH DIURNAL NORTHWEST WINDS RISING TO AROUND 5 KT
THIS AFTERNOON, THEN EASING THIS EVENING. -36
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...NONE.
WA...NONE.
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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