152
FXUS66 KPQR 040942
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
242 AM PDT SUN OCT 4 2026
SYNOPSIS
UNSEASONABLY WARM AND DRY CONDITIONS CONTINUE
THROUGH MUCH OF THE WORKWEEK WITH PERIODS OF OFFSHORE FLOW AND
EARLY MORNING VALLEY AND COASTAL FOG. A TROUGH MOVING INTO THE
PACIFIC NORTHWEST WILL BRING COOLER TEMPERATURES AND CHANCES FOR
RAIN FRIDAY INTO NEXT WEEKEND.
SHORT TERM...NOW THROUGH TUESDAY NIGHT
UPPER-LEVEL HEIGHTS
OVERHEAD PEAK TODAY BEFORE RIDGING CENTERED OVER THE DESERT
SOUTHWEST BEGINS TO SHIFT EASTWARD AND DE-AMPLIFY. A THERMAL
TROUGH ALONG THE COAST WILL ALSO SHIFT INLAND, WITH GOOD
AGREEMENT AMONG SHORT-RANGE ENSEMBLES THAT THE PRESSURE GRADIENT
BETWEEN PORTLAND AND THE DALLES OF AROUND -2 MB WILL WEAKEN
THROUGH THIS AFTERNOON, PUTTING AN END TO OVERNIGHT OFFSHORE
WINDS IN THE CASCADES AND FOOTHILLS. EAST WINDS GUSTING TO
20-30 MPH IN THE WESTERN COLUMBIA GORGE AND NEARBY TERRAIN WILL
THEREFORE EASE BY MIDDAY.
RIDGING ALOFT WILL ALSO PROMOTE AREAS OF OVERNIGHT AND EARLY
MORNING FOG IN SHELTERED COAST RANGE VALLEYS AND THE SOUTHERN
WILLAMETTE VALLEY THANKS TO LIGHT WINDS AWAY FROM THE CASCADES,
CLEAR SKIES, ROBUST NOCTURNAL INVERSIONS DURING INCREASINGLY
LONG NIGHTS, AND BROAD SUBSIDENCE WHICH ACTS TO COMPRESS THE
SURFACE LAYER. AS RIDGING ALOFT WEAKENS AND SOME HIGH CLOUD
COVER STREAMS OVERHEAD MONDAY AND TUESDAY NIGHTS, CHANCES FOR
DENSE FOG WILL GENERALLY DECREASE, BUT THE AREAS WHICH MAY SEE
RESTRICTED VISIBILITY FROM PATCHY FOG ACTUALLY BROADENS TO
INCLUDE MUCH OF THE I-5 CORRIDOR; COMMUTERS SHOULD CONSIDER
ALLOWING EXTRA TIME FOR THEIR MORNING TRIP TO WORK.
UPPER-LEVEL RIDGING WILL ALSO CONTINUE TO SUPPORT ABNORMALLY
WARM TEMPERATURES THROUGH THE PERIOD. MID-LEVEL TEMPERATURES
PEAK TODAY NEAR 20C, TRANSLATING TO AFTERNOON HIGHS IN THE LOW
TO MID 80S IN THE WILLAMETTE VALLEY AND ALONG THE I-84 CORRIDOR.
DAILY RECORD HIGHS ARE LIKELY OUT OF REACH FOR MOST SITES,
HOWEVER A RELATIVELY LOW RECORD OF 84F AT PORTLAND INT'L SET IN
1952 MAY BE IN JEOPARDY, WITH A 40% CHANCE OF TYING OR BREAKING
THE RECORD VALUE. DESPITE THESE WARM TEMPERATURES, THE MAJORITY
OF THE REGION WILL EXPERIENCE ONLY MINOR HEATRISK, WITH MODERATE
HEATRISK MOST LIKELY LIMITED TO CASCADE VALLEYS WHERE OFFSHORE
FLOW WILL SUPPORT WARMER LOW TEMPERATURES EARLY THIS MORNING.
OTHERWISE, THE PORTLAND-VANCOUVER METRO AREA MAINTAINS A 30-45%
CHANCE OF REACHING MODERATE HEATRISK, CORRESPONDING TO THE
CHANCES FOR SUNDAY MORNING LOWS TO FALL ONLY INTO THE UPPER 50S.
INLAND TEMPERATURES ARE EXPECTED TO COOL A FEW DEGREES MONDAY
AND TUESDAY AFTERNOONS AS ONSHORE FLOW RETURNS AND THE UPPER-
LEVEL RIDGE WEAKENS, BUT THESE TEMPERATURES WILL NONETHELESS
REMAIN SOME 5-10 DEGREES ABOVE NORMAL FOR EARLY OCTOBER. -36
LONG TERM...WEDNESDAY THROUGH SATURDAY
THE UPPER-LEVEL
PATTERN LOOKS TO AMPLIFY AGAIN THROUGH THE MIDDLE OF THE WEEK,
LEADING TO A SLIGHT WARMING TREND AS INLAND TEMPERATURES REMAIN
AROUND 10 DEGREES ABOVE NORMAL WEDNESDAY AND THURSDAY. DRY
WEATHER ALSO CONTINUES, WHILE THE RESURGENT RIDGE AND WARM
TEMPERATURES WILL AGAIN ALLOW FOR THE DEVELOPMENT OF A COASTAL
THERMAL TROUGH, NOCTURNAL OFFSHORE WINDS IN THE CASCADES AND
FOOTHILLS, AND EARLY MORNING VALLEY FOG IN THE COAST RANGE AND
WILLAMETTE VALLEY.
THERE IS INCREASING CONSENSUS AMONG LONG-RANGE ENSEMBLE MEMBERS
IN THE EVOLUTION OF AN UPPER-LEVEL TROUGH ARRIVING FRIDAY INTO
NEXT WEEKEND, BRINGING A RETURN TO MORE SEASONABLE TEMPERATURES
AND POTENTIAL RAINFALL. WHILE THERE IS STILL UNCERTAINTY IN
TIMING AND AMOUNTS, RAIN CHANCES PEAK FRIDAY AFTERNOON INTO
FRIDAY NIGHT, HIGHEST IN THE CASCADES AND ALONG THE COAST FROM
TILLAMOOK COUNTY NORTHWARD. -36
AVIATION...THROUGH 06Z MONDAY
CURRENTLY WIDESPREAD VFR
CONDITIONS INLAND AND LIFR CONDITIONS AT MOST COASTAL TERMINALS
AS MARINE STRATUS PUSHES INTO THE COASTLINE. THE ONE EXCEPTION,
KAST, HAS BEEN STAYING CLEAR AND VFR AS MARINE STRATUS PUSHES
SOUTHEASTWARD JUST SOUTH OF THE TERMINAL. LOOKING AHEAD, STRATUS
WILL LIKELY CONTINUE TO BUILD ALONG THE COAST AND MAY BRING
DETERIORATED CONDITIONS TO KAST BY 12Z SUN (20-30% CHANCE OF
LIFR CONDITIONS BETWEEN 13-17Z SUN). WHILE CHANCES OF VFR THEN
IMPROVE AFTER 17Z SUN AT KAST, CONDITIONS WILL LIKELY REMAIN
DETERIORATED AT KONP THROUGH MUCH OF THE TAF PERIOD. GUIDANCE
CONTINUES TO SUGGEST THAT KONP WILL STAY LIFR THROUGH AT LEAST
21Z SUNDAY AND MAY IMPROVE TO IFR THEREAFTER. AS FOR INLAND
TERMINALS, EXPECT VFR CONDITIONS THROUGH THE PERIOD, WITH JUST A
10-20% CHANCE OF LIFR CONDITIONS BETWEEN 12-17Z SUN. KEUG IS
THE ONE EXCEPTION WITH A 20-40% CHANCE OF LIFR BETWEEN THE
AFOREMENTIONED TIME.
WINDS CONTINUE TO EASE OVERNIGHT. EXPECT GENERALLY NORTH TO
NORTHWESTERLY WINDS OF 3-6 KT THROUGH THE PERIOD, WITH THE
EXCEPTION OF GUSTS UP TO 20 KT POSSIBLE AT KONP IN THE
AFTERNOON.
KPDX AND APPROACHES...VFR CONDITIONS THROUGH THE TAF PERIOD WITH
A 10-20% CHANCE FOR LIFR/IFR STRATUS BETWEEN 12-17Z SUN.
NORTHWESTERLY WINDS AROUND 3-6 KT. ~12
MARINE
PERSISTENT HIGH PRESSURE OFFSHORE WILL MAINTAIN
NORTHERLY WINDS THROUGH THE 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. 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.
HIGH PRESSURE ALOFT 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 PDT SUNDAY FOR VISIBILITIES OF 1 NM OR LESS
ACROSS THE WATERS SOUTH CAPE FALCON. CONFIDENCE FOR WIDESPREAD
DENSE FOG IS LOWER TO THE NORTH OF CAPE FALCON, BUT THE CHANCES
FOR RESTRICTED VISIBILITY ARE HIGHER NEARER TO THE COAST, AND
THE ADVISORY MAY BE EXPANDED IF OBSERVED CONDITIONS IN COASTAL
CLATSOP AND PACIFIC COUNTIES DEGRADE.
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. A LONGER PERIOD NORTHWESTERLY
SWELL MAY ALSO BRING A MODERATE SNEAKER WAVE THREAT. -36/10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...DENSE FOG ADVISORY UNTIL NOON PDT TODAY FOR PZZ252-253-272-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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