178
FXUS66 KPQR 040456 AAE
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
956 PM PDT Sat Oct 3 2026

Updated Aviation Discussion...

.SYNOPSIS...Abnormally warm and dry conditions will continue through
Thursday with periods of offshore flow and early morning fog within
sheltered valleys. The warmest temperatures will occur this weekend.
A potential trough approaches the region Friday into next weekend,
bringing cooler temperatures and increasing chances for rain.

&&

.SHORT TERM...Saturday evening through Monday night...An observed 500
mb height analysis from 5 AM PDT Saturday depicted large-scale
upper-level ridging over the Desert Southwest, with a ridge axis
extending through western/central Oregon and Washington. Model
ensemble guidance continues to suggest the ridge axis will gradually
shift eastward on Sunday, while a weak thermally-induced surface
trough shifts up the Oregon coast Sunday morning before shifting
inland in the late morning and afternoon. This set-up will favor
offshore flow with warm temperatures and dry conditions. East winds
will continue in the Cascades and western Columbia River Gorge now
through Sunday morning with wind gusts as high as 20-30 mph on
exposed ridgetops and in wind-prone areas of the western Gorge such
as Corbett, Crown Point, and Rooster Rock State Park. The strongest
winds are expected tonight and Sunday morning.

As ridging peaks overhead this weekend, mid-level temperatures
will rise to around 20C, yielding high temperatures at the
surface around 10-15 degrees above normal for early October. The NBM
continues to suggest inland valleys will warm to 80-85 degrees Sunday
afternoon, with highs in the upper 60s to lower 70s at the coast.
However, cool morning low temperatures will provide excellent relief
for those without air conditioning, resulting in only a Minor
HeatRisk. That said, offshore winds elevating overnight temperatures
within Cascade valleys and the Columbia Gorge will support localized
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 locations
are not expected to tie or break daily record highs (upper 80s to low
90s at inland sites), except a relatively low record of 84F at
Portland Int`l Airport set in 1952; this record has a 35% chance of
being tied or broken according to the latest NBM run. Temperatures
will cool several degrees on Monday as onshore flow returns and upper
level flow becomes zonal, resulting in highs of 75-80 degrees on
Monday, except 65-70 degrees at the coast. Even then, this is still
5-10 degrees above normal.

This pattern will also promote areas of fog tonight into Sunday
morning within the Willamette Valley and at the coast thanks to light
winds away from the Cascades, mostly clear skies, and robust
nocturnal inversions during increasingly long nights. Areas of dense
fog are most likely to occur at the coast, in sheltered Coast Range
valleys, and across the southern Willamette Valley (30-60% chance for
surface visibilities of 1/4 mile or less by 7-8 AM PDT Sunday per
REFS guidance). Chances for fog decrease along the coast are
relatively lower Sunday night/Monday morning, but expand in coverage
over the Willamette Valley, Cowlitz Valley, lower Columbia, eastern
Portland-Vancouver metro, and sheltered Coast Range Valleys.
Motorists commuting in the morning within these areas should consider
allowing extra time for their commute. -23/36


.LONG TERM...Tuesday through Friday night...The long term forecast
starts out dry with warmer than normal temperatures, and ends with
increasing chances for cooler weather and rain. The GEFS/GEPS/ENS
ensembles agree well on the synoptic-scale pattern Tuesday through
Thursday, suggesting broad upper-level ridging will remain in place
over the Pacific Northwest. It appears weak offshore flow will also
make a quick return. This pattern will favor cool mornings with areas
of valley fog, giving way to sunny and warm afternoons with highs in
the mid 70s to lower 80s for inland valleys and mid 60s to lower 70s
at the coast. Confidence for continued above normal temperatures is
very high (>90% chance). However, record high temperatures are highly
unlikely (<10% chance).

Chances for rain finally return to the forecast Friday into next
weekend with temperatures trending close to seasonal normals. By
Friday night, around 65-85% of the total ensemble space from the
GEFS/GEPS/ENS combined are showing measurable rain over southwest WA
and northwest OR within the 24-hour period ending at 5 AM PDT
Saturday. The highest probabilities are over southwest WA. Due to
significant timing differences in the start/stop time of
precipitation, 6-hourly NBM PoPs only peak between 10-30%. If rain
does occur, it could start anytime between early Friday morning and
late Saturday morning according to total model ensemble spread. -23

&&

.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 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. 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 building aloft through this weekend will also
support areas of dense fog developing nightly as cloud bases are
compressed down to the surface, especially within 40 NM of the
coast. Another Dense Fog Advisory has been issued from 11 PM this
evening through 12 PM Sunday for visibilities of 1 NM or less
across the waters south of Cape Foulweather and the waters
between Cape Falcon and Cape Foulweather. Confidence for
widespread dense fog is lower in the northern waters, but will
continue to monitor if the advisory needs to be expanded.

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. -10/36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Dense Fog Advisory until noon PDT Sunday for PZZ252-253-273.
&&


$$

www.weather.gov/portland

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