Eagle Tanner Trail, Oregon Weather Forecast Discussion

112
FXUS66 KPQR 242100
AFDPQR
Area Forecast Discussion
National Weather Service Portland OR
200 PM PDT Wed Sep 24 2025
.SYNOPSIS...Cooler temperatures are expected Thursday as onshore flow
strengthens. Another warming trend is expected over the weekend ahead
of an approaching frontal system, which looks increasingly likely to
bring rain to the region Sunday night into Monday. Conditions remain
cool and showery thereafter.
&&
.SHORT TERM...Wednesday night through Saturday night...The short term
forecast is highlighted by the continuation of dry weather with
seasonable temperatures, except Saturday which is trending around
five degrees above average for late September. Thursday morning will
start off chilly with temperatures in the mid 40s to lower 50s and
mostly clear skies. Abundant sunshine will allow temperatures to
quickly warm into the low to mid 70s across the lowlands Thursday
afternoon, except 60s at the coast. The HREF ensemble mean for cloud
cover suggests high clouds will increase from the northwest during
the late afternoon, after peak heating. High clouds should begin to
dissipate Thursday night, setting the stage for radiational cooling
given the calm winds in place at that time. As such, overnight lows
will trend even cooler with lows mainly in the mid to upper 40s,
except upper 30s to lower 40s in the Upper Hood River Valley.
Currently not expecting frost formation, even in the Upper Hood River
Valley, as the probability for lows of 36F or colder is less than 5%.
This seems reasonable as the Upper Hood River Valley and central
Columbia River Gorge will be the only locations with some wind during
the overnight hours, out of the west around 5-15 mph. This should
help limit how cold temperatures get and prevent frost formation.
Note forecast lows Thursday night are the coolest of any day over the
next seven days, so there are no signs of frost/freeze concerns at
this time.
Despite the chilly morning temperatures on Friday, temperatures are
expected to rebound nicely once again with highs in the mid 70s,
except 60s at the coast. Temperatures will warm even more on
Saturday, which will most likely be the warmest day for the
foreseeable future with highs in the mid 70s to lower 80s. That said,
there is a 10-25% chance highs only wind up in the low to mid 70s if
excess cloud cover develops. Model soundings show varying degrees of
high cloud cover, which may limit high temperatures if clouds are
thick enough during peak heating hours. -TK
.LONG TERM...Sunday through Tuesday night...The long term forecast is
highlighted by a transition to a cool and showery fall-like weather
pattern. The exact timing for precipitation to move into the area is
uncertain, as some model guidance suggests rain will begin as early
as Sunday morning or afternoon, while other guidance holds off until
Sunday night or Monday morning. That said, the vast majority of
ensemble guidance (over 80%) currently favors the latter solution,
keeping Sunday dry before the wet weather pattern takes hold Monday.
Assuming this solution comes to fruition, expect another mild day on
Sunday with high temperatures in the mid 70s, except low to mid 60s
at the coast. That said, if excess cloud cover and rain moves in more
quickly, high temperatures would likely top out in the 60s for both
the coast and inland valleys.
Despite the precipitation and temperature uncertainty on Sunday,
confidence is high for cool and wet conditions on Monday and Tuesday
as nearly every ensemble member from the ENS/GEFS/GEPS shows QPF by
that point, aside from a few dry GEFS members. NBM PoPs back this up
well, showing a 70-75% chance from the coast to the Cascades on both
days. Exact rain amounts are uncertain at this time, as ensemble
guidance suggests amounts could range anywhere from a few hundredths
of an inch to one inch. Will note the NBM suggests there is a 60-80%
chance for 0.25 inches of rain or more on both Monday and Tuesday.
-TK
&&
.AVIATION...High pressure over the region will maintain mostly
clear skies and VFR conditions through tonight. Reduced visibility
due to haze and mist along the coast will be possible again late
tonight with periods of MVFR conditions into Thu morning. Winds
increase out of the north and northwest this afternoon, strongest
along the coast with gusts up to 20-25 kt.
KPDX AND APPROACHES...VFR under mostly clear skies. Northwest
winds increase this afternoon, likely remaining below 10 kt. /DH
&&
.MARINE...High pressure offshore will maintain northerly breezes
across the coastal waters through Thursday evening. The strongest
winds are expected to persist through tonight with gusts up to
25-30 kt, with highest wind speeds from Cape Falcon southward.
The pressure gradient slackens somewhat on Thursday, but guidance
does suggest there is around a 60% chance of Small Craft Advisory
wind gusts across the inner waters south of Cape Foulweather by
Thursday afternoon. Elsewhere, gusts should remain 20 kt or less.
Seas around 7 to 10 ft today are expected to subside to around 5
to 7 ft on Thursday.
Winds ease by Friday as surface high pressure is pushed south by
a frontal system that is expected to stay to the north. This will
likely bring a mid-period northwest swell into the waters Friday
afternoon, building seas back up to around 7 to 9 ft at 14-15
seconds. Model guidance suggests the front stalls to the north on
Saturday, before reinvigorating, approaching the coastal waters
late this weekend. /Hartsock
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Thursday for PZZ251>253-
     271>273.
&&
$$
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NWS PQR Office Area Forecast Discussion