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FXUS66 KPQR 151809
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1009 AM PST Sat Nov 15 2025

.UPDATED AVIATION DISCUSSION...

.SYNOPSIS...A relatively drier pattern with upper-level ridging
atop a closed upper low over California will give way to a
progressive and active pattern early next week. Repeated systems
will bring cooler temperatures along with multiple chances for
lowland rain and mountain snow to the region.

&&

.SHORT TERM...Now through Tonight...The latest water vapor
satellite imagery features a prominent cutoff upper low centered
off the California coast while nearly zonal flow continues
overhead locally. Over the next 24 hours, upper-level ridging
will begin to build east of the Cascades, continuing to shift
eastward in tandem with the closed low slowly meandering inland
over California and Nevada. As ridging amplifies inland,
lingering light rain showers will continue to dissipate, with
the northern Oregon coast and Coast Range, southern Washington
coast, Willapa Hills, and the northern Oregon and southern
Washington Cascades remaining the most likely to see drizzle or
a brief rain shower through midday. Otherwise, dry conditions
are favored through tonight with overcast skies trending
clearer, especially from the southern Willamette Valley north
and west across the Cascades and Cascade foothills up to the
Columbia Gorge through this afternoon. Areas which see morning
rain and where sufficient clearing develops may be prone to
patchy fog overnight, most likely within sheltered Coast Range
valleys. Expect above-normal temperatures in the mid 50s to low
60s today and overnight lows largely in the 40s tonight. -36

.LONG TERM...Sunday through Friday...As upper-level ridging
pushes farther to the east through the middle of next week, a
progressive and active pattern takes hold in the Northwest. An
initial deep but narrow trough will approach the coast Sunday
into Monday, bringing a return of widespread rainfall chances to
the region by Sunday afternoon. There remains some uncertainty
around the evolution of this trough; the majority of global
ensemble members depict its development similar to the current
pattern, namely the flow may pinch the bottom of the trough into
a cutoff low affecting California while the energy associated
with the remaining weakened rump trough moves into the Pacific
Northwest, or the minority of members suggest it could maintain
a more coherent single elongated trough structure. Ultimately,
the precipitation forecast may be the most sensitive to the
details of the flow evolution, but both scenarios end with much
cooler air aloft advecting into the region by Monday.

With cooler air in place, temperatures will drop toward more
seasonable values during the workweek with daytime highs in the
upper 40s to mid 50s and overnight lows in the mid 30s to low
40s. As showers continue while troughing exits eastward through
Tuesday night, snow levels dropping to 3500-4500 ft could see
light accumulations at pass-level in the Cascades where
snowfall amounts remain very light through Tuesday. With less
than a 10% chance of more impactful amounts near 6 inches at
area passes, only minimal travel impacts are anticipated.

Following a brief dry stretch on Wednesday as narrow upper-level
ridging transits the region, another cutoff low along the coast
could see additional precipitation chances from Wednesday night
through Thursday night. Snow levels remaining around 4000-4500
ft could again see pass-level accumulations, although the
chances of 6 inches from 4 AM Wednesday through 4 AM Friday at
area passes remain only 10-20%. -36

&&

.AVIATION...This morning the region continues to see a mix of
flying conditions with VFR/MVFR to locally IFR (KTTD) at inland
terminals, and prevailing IFR conditions along the coast. Light
rain and mist/drizzle will gradually decrease south to north as
the morning goes on with dry weather returning for the afternoon
hours. Expect flight conditions to follow this trend as well at
inland terminals as generally MVFR CIGs improve back to VFR 20-22z
Sat, although there is still a 15-35% chance we hold onto
widespread MVFR beyond this point Portland Metro. At least visible
satellite looks promising with partial clearing beginning to take
place across the southern Willamette Valley - a transition in-line
with 12z high-res model guidance. However at the coast IFR
conditions are favored through the TAF period outside of the
Newport area where clearing likely yields a switch to MVFR CIGs
this afternoon.

Come the evening and overnight hours the focus switches to fog
formation which will be tied to the prevalence of clearing.
Greater clearing of cloud cover would yield an environment more
conducive to dense fog, especially in the Central/South Willamette
Valley with widespread LIFR impacts, while more persistent low
stratus at 2.5-3kft into the evening would trend CIGs more
MVFR/IFR. Given the latest guidance and observational trends,
confidence continues to grown for this fog scenario playing out at
least at KEUG and KSLE with a 70-80% chance for <0.5 mile VIS by
10-12z Sun at these sites. Slightly lower confidence further north
into the Portland Metro at this point with these probabilities
closer to 40-50% - something to watch. Winds remain fairly light
today, generally less than 10 knots.

KPDX AND APPROACHES...MVFR cigs prevail this morning with
intermittent light rain and mist/drizzle through 19-21z after
which point conditions likely begin to slowly improve to low-end
VFR. East-southeast winds at 5-10 kt this morning will ease below
5 kt by this afternoon into the evening. Chances (40-50%) for
further vis restrictions due to fog increasing 08-12z Sun, peaking
in likelihood 14-18z Sunday morning. -99

&&

.MARINE...Seas are expected to persist at 6-8 ft through the
weekend while southerly winds ease below 10 kt by this
afternoon. Another frontal system traverses the waters Sunday
into Monday, bringing increased southwesterly winds with gusts
to 20 kt before turning out of the northwest. Behind the front,
a building westerly swell will increase wave heights to 13-15 ft
by Monday morning, before falling below 10 ft again on Tuesday.
Should this forecast remain on track, an additional round of
Small Craft Advisories will be needed across the waters for this
event. Expect a fairly active weather pattern to continue
through the rest of the week as yet another system may bring
hazardous winds and seas later in the week, with increasing
chances for seas at or above 15 ft Thursday into Friday. -36/99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&

$$

www.weather.gov/portland

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