Four Corners, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

883
FXUS66 KPQR 050521 AAA
AFDPQR

Area Forecast Discussion...Updated
National Weather Service Portland OR
1021 PM PDT Mon Aug 4 2025

Updated Aviation...

.SYNOPSIS...Mean troughing will bring continued below-normal
temperatures through Thursday with cloudy mornings giving way to
afternoon sun inland. Clouds and chances for widespread rain increase
Tuesday night into Wednesday, before building high pressure brings a
warming and drying trend Thursday through the weekend.

&&

.SHORT TERM...Now through Wednesday Night...The short term forecast
is highlighted by increasing chances for measurable rain, beginning
Tuesday evening/night at the coast and Wednesday morning for inland
areas. This is in response to an upper level trough and attendant
pair of surface fronts that will bring abundant moisture to the area
with precipitable water values reaching an impressive 1.3-1.5 inches.
NBM 24-hour PoPs are now around 90% or higher across southwest WA,
the north OR coast/coastal mountains, Columbia River Gorge and north
OR Cascades/foothills. PoPs are near 70-80% over the Portland metro,
50% in the central Willamette Valley, 30-40% in the southern
Willamette Valley, and 20-30% over the Lane County Cascades. These
probabilities are in line with the latest suite of ensemble guidance,
as hardly any ensemble members are showing no rain at all to the
north of Salem. Although confidence is now high measurable rain will
occur for most locations north of Lane County, confidence remains
relatively lower regarding exact rain amounts as model spread for QPF
remains anywhere from a few hundredths of an inch to 0.5-1.0 inches.
The probability for at least 0.25 inches of rain has increased to
60-90% across southwest WA, 40-60% over the Portland metro and
northern/central Willamette VAlley, and 15-25% over Lane County.
Expect precipitation to begin as a steady stratiform rain before
transitioning to on-and-off rain showers Wednesday afternoon.
Post-frontal showers will likely continue through Wednesday night,
albeit most of the convection should be confined to the higher
terrain at that point. -TK


.LONG TERM...Thursday through Sunday night...Minimal changes have
been made to the long term forecast with today`s update. While cloud
cover and a few scattered rain showers may linger into Thursday
morning behind the departing system, a marked pattern shift will see
rising heights aloft atop resurgent surface high pressure over
the northeast Pacific. This flow regime will usher in a steady
warming and drying trend beginning Thursday and pushing
temperatures above normal by the weekend. By Sunday and next
Monday, 850-hPa temperatures of 20-25C could see surface
temperatures well into the 90s and approaching 100 degrees
across inland valleys, with 20-60% chances of highs exceeding
100F along I-5 from Portland/Vancouver southward. Also of note is dew
point temperatures will be running higher than usual during this warm
spell, likely in the mid 60s. This will make conditions feel
noticeably more humid. -Picard/TK

&&

.AVIATION...Clouds have continued to scatter out through the
evening, with VFR conditions prevailing across the area as of 05z
Tue. Little change otherwise, with VFR expected inland through the
period and MVFR conditions likely to return to KAST around 10z
Tue. KONP is the wildcard, with current mostly clear conditions
and light winds likely conducive to some localized fog
development overnight in the coastal plane. Added in some IFR
conditions after 09z Tue, but with low confidence in this scenario
as it is not well handled by the models. A frontal system will
approach late in the period, with rain and MVFR cigs possible at
KAST by around 03z Wed but likely holding off at other locations
until 06-12z Wed.

PDX AND APPROACHES...VFR with no major concerns. Around a 30%
chance for MVFR cigs 13-17z Tue. A frontal system approaches late
in the period, but do not expect any rain until after 06z Wed. /CB

&&

.MARINE...Minimal change in the forecast as a persistent pattern
will maintain relatively calm seas. Seas will be 3 to 5 feet
through the week and into next weekend. Winds will be
northwesterly 10-15 kt with gusts as high as 20 kt along the coast
and the far outer waters through early Tuesday. Due to the
northerly flow, the inner waters will see the gustier conditions
though will remain just below critical criteria.

On Tuesday, a low pressure system drops south into Haida Gwaii,
bringing southerly winds over the waters. Due to the location of
the low, wind gusts should remain below 25 kt, and wind waves will
see minimal response. The next period of potentially active marine
conditions will be on Friday afternoon. -Muessle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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