403
FXUS66 KPQR 022138
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
238 PM PDT Fri Oct 2 2026

.SYNOPSIS...Building high pressure with periods of offshore
flow will support warm and dry conditions through much of next
week. Early morning valley fog will be limited to sheltered
valleys, especially in the Coast Range.

&&

.DISCUSSION...Now through Thursday...Upper level ridging centered
over the desert Southwest will continue to dominate conditions
across the PacNW into at least the middle of next week, supporting
dry conditions and well above average temperatures. A shortwave
moving along the US-Canada border has kept the ridge slightly
suppressed today along with some cloud cover across western WA
and into the far northwestern portions of OR. Despite this,
temperatures are still expected to peak in the upper 70s across
the interior lowlands and mid 60s to low 70s along the coast.

Tonight into tomorrow, the upper level trough is expected to amplify
in the wake of the departing shortwave. 850 mb temperatures are
expected to jump into the 15-21 C range on Saturday and between 17-
22 C on Sunday. This is expected to translate to Saturday highs in
the upper 70s to low 80s across the interior lowlands and mid 60s to
low 70s along the coast. Sunday highs jump up into the low to mid
80s inland while coastal areas see similar temperatures to Saturday.
Most areas are not expected to reach record high temps, but the
relatively weak record of 84 degrees at PDX could be in jeopardy on
Sunday.

A weak thermal trough is expected to develop along the Oregon coast
tonight with a mean pressure gradient between Portland and the
Dalles of -2 mb and likely remaining less than -4 mb per short-range
ensembles. 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 in the
highest reaches of the Coast Range, before daytime mixing sees winds
decrease over terrain and increase out of the north within inland
valleys. Offshore winds look to peak Saturday night into Sunday
morning, with gusts of 20-30 mph in the Cascades and foothills,
highest in typical areas within and near the Columbia River Gorge.
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 are the most likely to
see areas of limited visibility, but the coverage of fog across the
region and possibly including the Willamette Valley remains
uncertain.

By Monday, confidence remains high in the upper level trough axis
shifting toward the center of the CONUS while also deamplifying,
allowing the overall flow to turn back onshore while bringing an end
to the locally breezier east winds. Forecast high temperatures lower
into next week but remain 5-10 degrees above normal across the
interior lowlands. Ensembles show good agreement in conditions
remaining dry through at least Thursday with the next chance for
rain coming late Friday or into next weekend with roughly 40-60% of
members depicting light rain. -19/36

&&

.AVIATION...Through 00Z Sunday...Currently widespread VFR inland
and a mix of VFR to LIFR at coastal terminals as northwesterly
winds push status into the coast. While inland terminals will
likely stay VFR through the period, chances of deteriorated
conditions increase after 11Z Sat, to around 10-20% for LIFR/IFR
conditions and 20-25% for MVFR conditions. As for coastal
terminals, there is rather low confidence of conditions before
06-08Z Sat as satellite shows stratus rebuilding and scouring out
along the coastline. From now until 08Z Sat, expect coastal
terminal conditions to bounce between VFR and LIFR as marine
stratus battles with wind. Beyond 08Z Sat, probabilistic guidance
suggests a 50-70% chance of LIFR and 60-80% chance of IFR
conditions until 16-18Z Sat, improving thereafter.

North to northwest winds around 3 to 6 kt this afternoon will
ease tonight around 06Z Sat and shift easterly at terminals near
the Cascade foothills and coastal gaps.

KPDX AND APPROACHES...VFR conditions likely through the TAF
period, with a 20-25% chance of MVFR and 10-20% chance of
LIFR/IFR conditions after 11Z Sat. Northwest winds 5 kt or less
throughout the period. ~12

&&

.MARINE...A weak system moving towards the US-Canada border
continues to bring west to southwest winds north of Cape
Foulweather this afternoon. Winds will shift back to northerly by
tonight and will remain in place into next week as high pressure
builds. Saturday and Sunday afternoon max wind gusts may exceed
20 kt, most likely within 20 NM of the coast. Seas continue at 3
to 6 ft through much of the next week. Northwesterly swell at 8
to 9 seconds will increase to 10 to 12 seconds early next week.
~12/36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.

&&

$$

www.weather.gov/portland

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