508
FXUS66 KPQR 070355 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
855 PM PDT Mon Oct 6 2025

Updated Aviation Discussion...

.SYNOPSIS...Conditions will remain dry with clear skies and
warm afternoon temperatures through Tuesday. Offshore flow with
breezy winds continue through Tuesday morning. Frost is likely
in the Upper Hood River Valley from Odell to Parkdale again between
1-9 AM PDT Monday. Temperatures trend cooler Wednesday onward.
Uncertainty remains regarding when rain showers will return to the
area, though most guidance holds off on precipitation until late
Friday or Saturday.

&&

.DISCUSSION...Monday night through Sunday night...Conditions will
remain dry Monday night as offshore flow continues over the area,
resulting in breezy easterly winds and poor overnight humidity
recoveries on exposed ridges in the Cascades and Coast Range. Max
wind gusts up to 30-40 mph are expected to continue on the most
exposed ridges. Winds will be much lighter in the Willamette and
Cowlitz Valleys, as well as sheltered valleys in the Cascade
foothills and Coast Range. The difference in winds between sheltered
valleys and exposed ridges will result in highly variable low
temperatures across mountainous terrain. For example, ridgetops in
the Cascade foothills will likely see low temps near 50 degrees,
while sheltered valleys will likely see lows in the upper 30s to mid
40s.

Similar to what was observed last night, the coldest locations should
be in the Upper Hood River Valley where widespread frost is likely to
occur again tonight. Another Frost Advisory has been issued for the
Upper Hood River Valley from 1-9 AM PDT Tuesday, which includes Odell
and Parkdale. Observed low temperatures across this zone Monday
morning ranged between 32-38 degrees, which was cold enough for frost
formation and impacts to sensitive vegetation. With
very little change to the weather pattern tonight, expect similar low
temperatures again, albeit a degree or two warmer due to slightly
warmer high temperatures this afternoon. Wind sheltered valleys in
the Cascade foothills and Coast Range also have the potential for at
least some patchy frost tonight, however confidence for low
temperatures below 37-38 degrees in these areas is not high enough to
warrant the issuance of a Frost Advisory. Based on observed lows from
last night and the expectation that lows will be 2-3 degrees warmer
tonight, suspect most locations in these zones will bottom out in the
upper 30s to mid 40 degrees rather than the mid 30s.

Despite the chilly temperatures that will be in place Tuesday
morning, temperatures will warm in a hurry in the afternoon. The NBM
continues to suggest high temperatures ranging between 75-80 degrees
across the lowlands, except 65-73 degrees at the coast. It appears
Tuesday will be the last 70+ degree day for the foreseeable future as
highs cool into the 60s from Wednesday onward. Models and their
ensembles remain in agreement on Wednesday, showing seasonable
temperatures with lighter winds and continued dry weather.

The forecast remains uncertain on Thursday, especially in regards to
rain amounts, or lack thereof. The uncertainty lies with the exact
location of a closed upper level low that will be settling somewhere
over the coastal waters late in the week. Most model guidance keeps
this low far enough to the west to maintain dry to mostly dry
conditions on Thursday, which NBM PoPs back up well. PoPs currently
peak between 25-30% on Thursday, which means odds currently favor no
rain at all. The exception is in the Cascades where PoPs increase to
40-50%. Despite the forecast uncertainty in place on Thursday,
confidence remains high for widespread rain showers late Friday into
Saturday as the aforementioned low pressure system finally pushes
inland. This is also when the NBM is showing a 40-60% chance for at
least 0.25 inches of rain. -23

&&

.AVIATION...High pressure persists overnight into tomorrow,
maintaining offshore flow at the surface and clear skies with VFR
conditions through the TAF period. Along the coast, expect
easterly winds under 10 kt until 18-20Z Tuesday, then northwesterly
winds around 8-12 kt. Inland, winds will be generally easterly and
under 10 kt overnight, then light and variable during the day.
KTTD will be an exception, with easterly wind gusts up to 20-25 kt
until 18Z Tuesday, then easterly under 10 kt through the rest of
the period.

KPDX AND APPROACHES...VFR and clear skies through the period.
Mostly easterly winds under 10 kt, becoming light and variable by
18Z Tuesday.
~12

&&

.MARINE...High pressure offshore combined with a thermal trough of
low pressure along the coast will maintain northeasterly winds
across the waters through Tuesday morning. Low pressure shifts
inland on Tuesday as a weak cold front approaches the waters as
winds become more north to northwesterly by Tue afternoon. Wind
gusts later today are generally expected to around 20 kt or less,
except isolated gusts up to 25 kt across portions of the outer
coastal waters, mainly beyond 40 NM. Winds are expected in
increase Tue afternoon into Tue night, with more widespread gusts
to 25 kt. Seas around 3 to 5 ft are expected to persist through
Tue morning, before building to around 7 to 8 ft Tue night.
Therefore, have issued a Small Craft Advisory for Tue afternoon
through Tue night.


An area of weak low pressure approaches the coastal waters on
Wednesday while winds are expected to weaken, followed by
offshore flow on Thursday as the surface low continues to drop
south. Seas are likely to linger around 6 to 7 ft through the end
of the week.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Frost Advisory from 1 AM to 9 AM PDT Tuesday for ORZ121.

WA...None.
PZ...Small Craft Advisory from 4 PM Tuesday to 2 AM PDT Wednesday for
     PZZ210.

     Small Craft Advisory from 4 PM Tuesday to 5 AM PDT Wednesday for
     PZZ251>253.

     Small Craft Advisory from noon Tuesday to 5 AM PDT Wednesday for
     PZZ271>273.
&&

$$

www.weather.gov/portland

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