178
FXUS66 KPQR 101114
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
314 AM PST Mon Nov 10 2025

.SYNOPSIS...A weak shortwave trough will bring light showers and
increased low to mid-level clouds to the region. Drier weather
briefly returns on Tuesday as high pressure builds. A pattern
change to cooler and wetter weather returns on Wednesday. Snow
levels fall Thursday to Friday, returning chances for snow at
the Cascade passes. Active weather continues into the weekend.

&&

.SHORT TERM...Today through Tuesday night...Radar and satellite
imagery as of early Monday morning depicts mid to high level
clouds moving into northwest Oregon and southwest Washington as
a weak front brushes the region. Prior to these clouds moving
in, clear skies, calm winds, and a moist surface supported the
development of dense fog in the southern Willamette Valley.
Based on surface observations, dense fog is resulting in
visibility of one quarter mile or less in this area. Therefore,
a Dense Fog Advisory has been issued for the southern Willamette
Valley including Eugene, Creswell, and Cottage Grove through 10
AM this morning. If commuting, make sure to slow down, use your
low beam headlights, and leave plenty of distance ahead of you.

Circling back to the weak front that`s moving in, some light
showers have begun along the north OR and south WA coast, and
hi-res guidance suggests that these showers will gradually
spread inland this morning. Since this weak front is tracking
mostly to the north of us, most of the rain is being directed
toward western Washington and southern British Columbia. Chances
for even receiving any measurable rain today (0.01" or more)
is only 30-50% across the Willamette Valley and southwest WA
lowlands based on the REFS. The wettest areas today would
likely be along the south WA coast, and north OR/south WA
Cascades and foothills where chances for receiving 0.10" of rain
or more are around 20-40%.

Easterly winds through the Columbia River Gorge have finally
begun to weaken as the pressure gradient from Troutdale (KTTD)
to The Dalles (KDLS) has eased to about -1 mb. Expect winds
today to be out of the south/southwest around 5 mph or less,
shifting more northwesterly this evening as weak surface high
pressure builds.

A shortwave ridge builds on Tuesday, briefly returning drier
conditions. However, an active weather pattern is in store for
the remainder of the week, which will maintain onshore flow
with widespread precipitation and cooler temperatures (see long
term discussion).       -10

&&

.LONG TERM...Wednesday through Sunday...A deep upper level
trough over the NE Pacific will approach the Pacific Northwest
late Tuesday night into early Wednesday morning. A cold front
associated with this upper trough will push through the region
and bring widespread rain across northwest Oregon and southwest
Washington by Wednesday afternoon. There still remains
uncertainty with the exact track and strength of the low, and
thus precipitation amounts. For now, chances for 24 hour (4 PM
Wednesday to 4 PM Thursday) rain totals to exceed 1 inch are
around 15-30% across interior lowland valleys, and 50-70% along
the coast and Coast Range.

Once this cold front pushes through, it will bring much cooler
air to the region on Thursday. Cooler air aloft will support a
more unstable atmosphere and thus lead to potential convection.
There is currently a 10-20% chance for thunderstorms on
Thursday west of the Cascades, with the highest chances along
the coast. Any passing thunderstorms could produce lightning,
heavy downpours, gusty outflow winds, and small hail.

The majority of ensemble guidance also suggest that 850 mb
(5000 ft) temperatures will fall to around -1 to -4 deg C
Thursday to Friday, which would result in snow levels falling
to pass level in the Cascades. Current guidance suggests a
70-80% chance that 48-hour snow totals between 4 AM Thursday to
4 AM Saturday exceeds 6 inches at Santiam and Willamette Passes,
while chances are lower around 40-50% at Highway 26 near
Government Camp. Those traveling to the Cascades at the end of
the week should be sure to monitor the forecast and check on
road conditions via ODOT/WSDOT before heading out.

Heading into Saturday, warmer air will be introduced as a warm
front from another system approaches the Pacific Northwest. This
will briefly bring snow levels up above pass-level and maintain
wet weather through the weekend.        -10

&&

.AVIATION...BKN/SCT high clouds continue to spread across
northwest Oregon as a weak front moves through the region. CIGs
have fallen to IFR/MVFR along the coast with this front, and
there is high confidence (>90% chance) that this trend will
continue along the coast through 20-22z Mon. Ahead of the high
cloud cover associated with the front, areas of fog/mist and low
stratus have developed across parts of the central and southern
Willamette Valley, bringing LIFR/IFR CIGs and VIS. This trend
continues until around 12-13z Mon when the front makes its way
into the Valley and brings more showers and mixing. This mixing
will help dissipate any fog and improve VIS and CIGs to
MVFR/low-end VFR thresholds. Guidance suggests a 60-80% chance
for MVFR CIGs with the frontal passage between 12-18z Mon for
the northern Valley, and 18z Mon-00z Tue for the central and
southern Valley. After 00z Tue, conditions begin to trend more
VFR for most terminals as the front exits the region, but
coastal terminals maintain a 30-50% chance for IFR/MVFR CIGs.

Easterly winds around 15 kt with gusts up to 20 kt continue
through the Columbia River Gorge and eastern Portland Metro
(KTTD) as of early Monday morning, however, pressure gradients
between KTTD and KDLS are forecast to gradually ease throughout
the morning. This will weaken easterly winds. Elsewhere, winds
today are generally southerly to southwesterly around 5 kt or
less, turning more northwesterly in the afternoon.

KPDX AND APPROACHES...VFR conditions until 15-17z Mon when
chances for MVFR CIGs increase to 50-70% with the frontal
passage. After 20-21z Mon, expect conditions to improve to VFR
as the front exits the region. Easterly winds less than 5 kt
today, turning more northwesterly this afternoon/evening.
                                                     -10

&&

.MARINE...Winds as of early Monday morning are southerly to
southwesterly around 5-10 kt as a weak front pushes through the
waters. Expect winds to gradually shift westerly this morning as
the front progresses inland. By this afternoon, weak high
pressure will rebuild and winds turn northerly. Seas generally
remain 7-9 ft at 11 seconds today. Benign marine conditions
continue through Tuesday night with variable winds and gusts
remaining around 10 kt or less. High confidence (>95% chance)
that seas remain below 10 ft through early Wednesday morning.

The next low pressure system in the NE Pacific will return
breezy  southerly winds and building seas Wednesday into
Thursday, with high confidence for another period of conditions
hazardous to small craft. As this system swings a front through
the waters, we`ll likely (60-80% chance) see frequent southerly
wind gusts exceeding 21 kt and a >90% chance that seas build
above 10 ft by Wednesday night. There is also a 40-60% chance
for isolated gale-force wind gusts greater than 34 kt
Wednesday-Thursday, with the highest chances across the outer
waters beyond 20-30 NM. Active weather continues into the end of
the week with additional systems moving through the waters.
                                                      -10

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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