Willamette Mission State Park Oregon Weather Forecast Discussion

198
FXUS66 KPQR 131818 AAA
AFDPQR
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1118 AM PDT Mon Oct 13 2025
Updated aviation discussion.
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.SYNOPSIS...A cool and unsettled pattern continues across the
Pacific Northwest through today as a broad upper-level trough,
with its center low currently over the region, maintains a slow
southeastward progression. Showers and mountain snow will
continue this morning before tapering off later today as the
system exits. Temperatures will remain below seasonal averages
through tonight. A ridge of high pressure then builds overhead
beginning Tuesday, ushering in a warmer and drier trend through
midweek. Model guidance diverges toward the end of the week
regarding the potential return of a coastal low and increasing
cloud cover.
&&
.DISCUSSION...Now through Saturday...Showers continue early this
morning across parts of northwest Oregon and southwest
Washington, with locally heavier bursts near the Cascade
foothills. The center of the low is currently positioned over
the region, supporting ongoing precipitation. Satellite and
radar imagery show scattered showers, which are expected to
gradually diminish through the day as the trough continues
southeastward.
Colder air aloft has lowered snow levels to around 4000 to 5000
feet, producing accumulating snow across the Cascades. A Winter
Weather Advisory remains in effect for elevations above 4000
feet through this morning. Cascade passes will likely see 1 to
2 inches more of wet snow through the morning, while Highway 26
near Government Camp may see an additional trace to half of an
inch. Above 5000 feet for areas north of The Three Sisters,
expect an additional 3 to 7 inches through this morning, which
could still impact travel on unmaintained roads.
As the trough moves southeast later today, skies will gradually
clear, setting the stage for colder overnight temperatures. In
the Upper Hood River Valley, a Frost Advisory remains in effect
until 9 AM this morning due to reduced cloud cover and efficient
radiational cooling. For tonight, a Freeze Warning is in effect
from 12 AM to 9 AM Tuesday for the same area, where temperatures
are expected to fall below freezing. The probability of
temperatures at or below 32 degrees ranges from 50 to 90
percent, while the probability of 28 degrees or colder ranges
from 5 to 35 percent, highest to lowest from Parkdale to Odell.
Sensitive vegetation and unprotected plumbing may be affected.
In addition, Frost Advisories have been issued for tonight from
12 AM to 9 AM Tuesday across several other locations expected
to experience similar cooling under clearing skies. These
include the Lane County Cascade Foothills, Lane County Lowlands,
Linn County Lowlands, North Oregon Coast Range Lowlands, South
Washington Cascade Foothills, and Cowlitz County Lowlands. These
areas are likely to see patchy frost and near-freezing
temperatures capable of damaging unprotected plants and crops.
With easterly winds in the forecast, there is some uncertainty
on which locations may or may not cool toward these forecasted
temperatures.
From Tuesday through Thursday, ensemble and deterministic
guidance supports a broad ridge over the Pacific Northwest,
bringing warmer and drier weather. Highs will moderate into the
mid to upper 60s across the lowlands, coast, and Coast Range,
with upper 40s to upper 50s across the Cascades. Toward Thursday
and into the weekend, forecast confidence decreases as model
solutions diverge. Some guidance indicates a shortwave trough
may approach the coast late in the week, which could result in
increasing cloud cover and light precipitation returning to
parts of the region.
~12
&&
.AVIATION...The surface low that supported light showers across
the area continues to drop southward, supporting clearing from
south to north. Cloud cover remains over the Willamette Valley
from Salem southward but is expected to clear by early afternoon.
Winds have shifted to the north through the Willamette Valley and
with a stronger offshore component along the coast. Wind gusts
20-25 kt expected for all sites through the evening. VFR
conditions expected through the tonight and into Tuesday morning.
KPDX AND APPROACHES...VFR conditions expected through the TAF
period. Northerly winds shifting to the east this afternoon with
wind gusts to around 20 kt. /19
&&
.MARINE...A low pressure systems currently located over the
region continues to slowly move southward. This will bring gusty
north to northeasterly winds through today for most of the
waters. Small Craft Advisory conditions are expected to persist
until 11 PM Monday for the central and southern waters, and
until 5 PM for the northern waters. As the low moves southward
through today, seas currently around 8-10 ft will decrease. An
offshore pressure gradient will maintain northeasterly winds
into Tuesday, shifting back to onshore flow late Tuesday. Seas
will drop to 5-7 ft at 8-10 seconds Tuesday.
While the weather pattern remains a bit uncertain for this
upcoming weekend, model guidance for wave height has improved. On
Saturday, there is moderate to high confidence for seas around 8
to 10 ft. Greater uncertainty remains for Sunday, with an 80%
chance for seas between 9 and 15 ft. ~12
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory from midnight tonight to 9 AM PDT Tuesday for
     ORZ104-117-118-125.
     Freeze Warning from midnight tonight to 9 AM PDT Tuesday for
     ORZ121.
WA...Frost Advisory from midnight tonight to 9 AM PDT Tuesday for
     WAZ204-208.
PZ...Small Craft Advisory until 5 PM PDT this afternoon for PZZ251-
     271.
     Small Craft Advisory until 11 PM PDT this evening for PZZ252-
     253-272-273.
&&
$$
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NWS PQR Office Area Forecast Discussion