303
FXUS66 KPQR 191250
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
450 AM PST Wed Nov 19 2025

.SYNOPSIS...Another coastal weather system will brush the area
tonight into Thursday morning bringing light rain, with dry
conditions otherwise expected through the workweek. The pattern
then shifts wetter and colder this weekend into early next week.

&&

.SHORT TERM...Now through Friday Night...Wednesday will see a
cool and dry start, with pockets of valley fog and frost where
skies have remained clear overnight. A dry offshore wind will
help scour out low clouds and fog through the morning,
especially west of terrain gaps including the Columbia River
Gorge, while some areas in the central to southern Willamette
Valley may remain stuck beneath a low overcast into the early
afternoon. Generally seasonable temperatures are expected today,
although areas which remain foggy or cloudy will struggle to
hit even 50 degrees before sunset.

A negatively-tilted trough and surface occluded front will
approach the coast by late this afternoon, before splitting to
form a closed upper low which will dive south into California
on Thursday. Light rain will begin along the coast most likely
by 8-11 PM Wednesday, spreading inland to the I-5 corridor by 10
PM Wednesday-1 AM Thursday, although a reasonable earliest
onset time could be about 2 hours earlier in the evening. As the
developing low tracks southward, rain will become more showery
in distribution and end by the mid-afternoon on Thursday. Given
the expected evolution of this system, highest rainfall totals
will be along the coast, in coastal terrain, and to the south
across Lane County where 0.2-0.5" is expected. The central
Oregon coast including coastal Lane County will be the most
likely to see 0.5" of rain or more. Interior areas from Linn and
Benton Counties northward are more likely to see 0.05-0.15" of
rainfall, although the Cascades may see higher precipitation
totals as well. Snow levels will remain above 5000 ft through
much of the event, dropping closer to 4500 ft by Thursday
morning. This may allow up to a half inch of snow to accumulate
at Willamette and Santiam Passes, but little in the way of
travel impacts are expected.

In the wake of the departing upper low, broad but low-amplitude
ridging will develop over much of the western half of the
country on Friday. This will keep the mid-latitude jet and
primary storm track pointed toward Vancouver Island. Rain
chances will therefore be higher across western Washington and
decreasing southward into western Oregon, leaving much of the
region on the drier side to end the workweek. -36


.LONG TERM...Saturday through Tuesday...This weekend into early
next week, the ridge axis will slowly slide eastward toward the
Rockies, allowing the storm track to dip south into the Pacific
Northwest and resulting in steadily increasing chances for
precipitation across the region. Global ensembles remain in
fairly good agreement given the lead time that an upper-level
shortwave trough will track toward western Washington or
northwestern Oregon, although the timing of this feature
remains more uncertain, ranging anywhere from Sunday night
through Tuesday. Additionally, the ensemble mean mid-level
temperatures overhead have continued to trend warmer through the
period in question, supporting a scenario where even if
plentiful moisture and synoptic lift are present, the column
may simply be too warm to see impactful snow at pass-level. As
such, the chances for 6 inches or more of snow have fallen
substantially to 5-10% at the Cascade passes from Sunday through
Tuesday. On the heels of this shortwave, however, another shot
of colder temperatures could reach the region toward the middle
of next week. -36

&&

.AVIATION...High pressure remains in place overhead, supporting
widespread inland fog early this morning. Light and variable winds
will become easterly at Portland-area terminals by 15-18z Wed, and
this drier east flow will aid in clearing low clouds. KTTD is
unlikely to see restricted vis/cigs as long as light east flow
remains in place, but there remains a 10-20% chance that fog
encroaches from the west if winds slacken. Elsewhere in the
Willamette Valley, fog and low clouds will be slow to scour out as
low-level flow is likely to remain very light through much of the
morning, meaning terminals may not clear until 18-21z Wed.

Along the coast, east flow at KONP will likely maintain VFR
conditions, however a few low cloud may yet sneak through coast
range gaps, albeit not with enough coverage to restrict flight
categories. To the north at KAST, favored east-southeast flow will
see intermittent vis restrictions within fog, before conditions
improve by 16-18z Wed as winds strengthen.

Late in the period, by 02-03z Thu at the coast 04-06z Thu inland,
an occluded front will move onshore. This will see winds build out
of the south for most of the region, and out of the southeast at
Portland-area terminals. On the coast, southerly gusts of 15-25 kt
are expected. The frontal passage will yield light rain with
60-70% chances of MVFR cigs at all terminals this evening.

KPDX AND APPROACHES...Intermittent IFR/LIFR fog has developed and
are expected to continue until drier east winds reach the
terminal, most likely by 15-16z Wed but with a 10-15% chance of a
low stratus deck lingering as late as 18-19z Wed if winds are
slow to strengthen. VFR conditions will then prevail through the
afternoon, until a frontal passage will see light rain and an 80%
chance of MVFR cigs after 06z Thu. -36

&&

.MARINE...Fairly tranquil conditions in place early this morning
with regional buoys reporting 5 ft seas at light east winds of
5-10 kt, although locally stronger winds may exist west of gaps
in coastal terrain. Winds will turn out of the south and build to
around 20 kt gusting to around 25 kt through this afternoon ahead
of an approaching frontal boundary while seas build to 6-8 ft with
a dominant west-northwest swell. Small Craft Advisories will go
into effect at 1 PM across the outer waters beyond 10 NM, and at 7
PM across the inner waters due to these gusty south winds.

While south to southeast winds will ease to around 10 kt through
tonight, a rapidly building long-period westerly swell will see
seas climb to 16-19 ft by Thursday afternoon and evening. As
such, Hazardous Seas Warnings have been hoisted across the coastal
waters from 10 AM Thursday through 4 AM Friday, spanning the time
when seas are forecast to remain above 15 ft. At the same time,
steep seas of 10-14 ft will make for a hazardous crossing of the
Columbia River Bar, especially during a strong ebb tide Thursday
afternoon, coinciding with some of the highest seas. A Small
Craft Advisory is therefore also in effect for the bar from
midday Thursday through Thursday night.

The long-period westerly swell will ease on Friday, but remain at
10-12 ft into early next week, allowing elevated seas to persist
through at least Monday. Southwesterly winds around 10 kt will
also continue through Sunday before turning out of the north at
10-15 kt on Monday. -36

&&

.BEACH HAZARDS...An energetic westerly swell is expected along
the northwestern Oregon and southwestern Washington coasts for a
long duration from Thursday through next Monday. Initially, the
swell will reach 15-18 ft at 15 seconds through much of Thursday,
before weakening slightly to 10-12 ft at 12-15 seconds from early
Friday afternoon through the the weekend. Even when this swell is
slightly lower amplitude, its long-period nature will yield a high
risk for sneaker waves along area beaches. These energetic waves
can run significantly farther up a beach than normal, including
over rocks and jetties, creating potentially life-threatening
conditions in the surf zone when beachgoers can be unexpectedly
knocked off their feet and pulled out into cold ocean waters.

A Beach Hazards Statement has therefore been issued from 5 AM
Thursday through 5 AM Monday. Caution should be used when in or
near the water, and beachgoers with children should be especially
watchful. Never turn your back on the ocean, and be sure to keep
an eye on the waves. Those participating in razor clam digs should
additionally exercise caution. -36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.

WA...None.

PZ...Small Craft Advisory from 10 AM Thursday to 4 AM PST Friday
     for PZZ210.

     Small Craft Advisory from 7 PM this evening to 10 AM PST
     Thursday for PZZ251>253.

     Hazardous Seas Warning from 10 AM Thursday to 4 AM PST Friday
     for PZZ251>253-271>273.

     Small Craft Advisory from 1 PM this afternoon to 10 AM PST
     Thursday for PZZ271>273.

&&

$$

www.weather.gov/portland

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