729
FXUS66 KPQR 040557 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
956 PM PST Tue Nov 3 2026

Updated aviation and marine discussions.

.SYNOPSIS...After ample valley fog/low stratus to start Wednesday
morning, a frontal boundary arriving Wednesday afternoon will
kick of an active and wetter weather the remainder of the week
and beyond. Still, these conditions will be mixed with temporary
periods of dry weather in-between systems, and slightly warmer
than average temperatures. At least weather related impacts
over the next 5-7 days stay fairly limited overall.

&&

.DISCUSSION...Now Through Monday...Conditions trend completely
dry and calm this afternoon into the evening hours as an upper-
level low centered near the northern California/Oregon boarder
progresses further eastward and a transient ridge of high
pressure hurriedly builds overhead tonight. The eventual return
of widespread clear skies and light winds likely allows for
efficient radiational cooling as temperatures fall into the mid
30 to low 40s. Thanks to these conditions and ample lingering
surface moisture, fog development increases into early Wednesday
morning as the surface inversion deepens. Come the sunrise hours
Wednesday morning, models like the REFS are very bullish on fog
formation across our inland valleys areas, especially in the
central/south Willamette Valley and in the more protected coast
range valleys. If you encounter dense fog Wednesday morning,
remember to keep your vehicle headlights on and slow down. Fog
likely transitions to a low stratus layer by midday Wednesday
before breaking up.

Afternoon temperatures Wednesday rise into the mid 50s to near
60 degrees as southerly winds increase ahead of our next
approaching weather disturbance in the form upper level
shortwave trough moving across the NE Pacific. This feature is
slated to arrive later Wednesday afternoon at the coast,
spreading inland by Wednesday evening. Chances for widespread
rain peak Wednesday night at around 85-100%, though
precipitation amounts remain relatively low. Mean QPF values
ranging from around 0.10-0.30 inch while chances for exceeding
0.50 inch are highest along the coast (20-40%) and south
WA/north OR Cascades and foothills (30-45%). A few lingering
showers will be possible into Friday morning, though Thursday
likely will see an extended dry period the latter half of the
day with temperatures warming again a few degrees above normal.

Then on Friday, cluster analysis of 500 mb heights looks
relatively similar with southwest flow aloft over the NE Pacific
and weak upper level ridging nudging into the PacNW. But, there
are subtle differences that will determine whether areas remain
dry or wet weather returns to end the week. This still largely
depends on the strength of the upper ridge and where the
northern jet stream, which will likely be associated with
atmospheric river moisture, will be directed towards. The latest
clusters show the wetter solution is dominated by the European
ENS (southern jet solution), while the GEFS (northern jet
solution) is hedged toward a drier forecast for much of the
forecast area by keeping much of the precipitation just to the
north. So, still quite a bit of uncertainty in the forecast.

There remains decent confidence in the forecast over the
weekend as ensembles are in good agreement depicting broad
troughing over the Pacific pushing the upper level ridge farther
east over the Rockies. Temperatures are likely to warm well into
the 60s across the area on Saturday before a frontal system
spreads rain across the Pacific Northwest late Saturday into
Sunday. All that being said, no significant precipitation
impacts are expected with any of these weather systems over the
next 5 to 7 days, and snow levels hold around 5000-6000ft before
lifting again this weekend. Keep in mind storm drains tend to
get easily clogged this time of year. However, beyond day 7
into next week (11/11-11/15), a large number of ensemble
systems are beginning to show a growing consensus for a
potentially more impactful and active weather pattern. -99/DH

&&

.AVIATION...Through 06Z Thursday...Satellite and surface weather
observations from 0530Z Wednesday depicted broken high clouds over
the central and northern Willamette Valley into the Portland,
resulting in broken to overcast skies at KSLE, KUAO, KHIO, KTTD,
and KPDX with ceilings around 8000-9000 ft. If this cloud deck
lingers through much of tonight, fog development will be limited.
Confidence is high KTTD will remain VFR with no fog development
due to a combination of the aforementioned cloud deck and
continued breezy easterly winds around 10 kt with gusts up to
around 20 kt. Confidence is relatively lower at KUAO, KSLE, KHIO,
and KPDX; probabilities for surface visibilities below 1 SM at
these TAF sites are around 20-40% between 12-17Z Wednesday, except
near 50% at KHIO. KEUG also has a 20-40% chance for surface
visibilities below 1 SM. Meanwhile, light offshore winds at KAST
and KONP should be enough to prevent fog development at the
coastal TAF sites.

Overall, VFR flight conditions are the most likely outcome
through 22-00Z for coastal terminals and through 03-05Z for inland
terminals. Chances for MVFR ceilings below 3000 ft increase
rapidly towards 00Z at the coast and around 06Z inland as a front
moves inland and brings a band of light stratiform rain with it.
Rain will begin ahead of the frontal passage, most likely between
21-23Z at the coast and between 00-02Z inland. Breezy south winds
are expected at the coast as the front moves inland, with gusts as
high as 20-25 kt.

KPDX AND APPROACHES...Expect predominately VFR conditions to
continue through 06Z Thursday. There is a 20-40% chance for
surface visibilities below 1 SM between 12-17Z Wednesday, however
confidence is not high enough to reflect this in the TAF. Light
rain is expected to begin sometime between 00-02Z Thursday ahead
of an incoming front. Chances for ceilings below 3000 ft increase
at 06Z Thursday to around 40%. -23

&&

.MARINE...Light south winds continue over the coastal waters this
evening as high pressure remains in place. A WNW swell continues
to maintain seas around 8 to 9 ft at 13 to 14 seconds per the
latest buoy observations. Seas are expected to decrease by one or
two feet early Wednesday morning.

Another frontal system is then expected to bring gusty southerly
winds and steep seas to the waters Wednesday afternoon. Small
Craft Advisories have been issued for all the zones for varying
times with the main focus between 10 AM through 10 PM Wednesday as
the the front moves through the waters. Winds are expected to be
strongest for waters north of Cape Falcon with gusts to around 30
possible. Waters south of Cape Falcon to Florence could experience
gusts up to 25 kt. Seas 6 to 7 ft at 15 seconds expected.

The active pattern is expected to continue for the latter half of
the week and into the weekend. A westerly swell is expected to
enter the waters late Wednesday night into Thursday, pushing seas
above 10 ft at 14 to 15 seconds which would be steep and dangerous
to small craft. Headlines may need to be extended past their
current 10 PM Wednesday expiration. Another front approaches late
Thursday into Friday bringing another round of southerly wind
gusts between 25-30 kt. There is a 20-40% chance for Gales for the
waters north of Cape Falcon. Seas expected 11 to 14 ft at 15 to
17 seconds with a 10-20% chance seas exceed 20 ft. The hits keep
on coming as another front could move through on Saturday with
gusty winds and steep seas. -19/23

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 1 PM to 10 PM PST Wednesday for
     PZZ210-251-252-272.

     Small Craft Advisory from 1 PM to 7 PM PST Wednesday for PZZ253-
     273.

     Small Craft Advisory from 10 AM to 10 PM PST Wednesday for
     PZZ271.
&&

$$

www.weather.gov/portland

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