122
FXUS66 KPQR 170425 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
825 PM PST Sun Nov 16 2025

Updated Aviation Discussion

.SYNOPSIS...Light rain continues through Monday morning. A
passing ridge will support mostly dry conditions on Tuesday and
Wednesday. The next impactful system takes aim at the region
during the latter half of the week. There is uncertainty in the
progression of this system but rain and mountain snow are
possible.

&&

.SHORT TERM...Now through Tuesday Night...Dreary fall
conditions expected today as thick, low clouds cover the region.
A cold front continues to move toward the coast supporting
light rain and misty conditions which has kept visibility
generally less than 5 miles. The narrow trough supporting the
front is expected to split, with the base of the pinching off
and forming a cut-off low that drops southeast along the West
Coast. The northern portion of the trough moves eastward.
Rainfall totals with this system will be on the lower side given
the splitting of the upper level trough leaving the area under
weaker forcing. Inland totals through Monday morning expected to
be 0.25-0.50 inches while along the coast and higher terrain,
totals closer to 0.75 inches will be possible. Snow levels for
the Cascades are expected to remain above 6000 feet until the
trough axis passes overhead early Monday morning and much colder
air filters in overhead. Snow levels drop to 2500-3500 feet
Monday night into Tuesday morning but QPF will be much lower by
this time. Not expecting any substantial snowfall at pass level
with this system. Cooler surface temperatures are also expected
on Monday and Tuesday with the passage of this system. Expect
inland and coastal highs in the low to mid 50s and highs in the
40s for the higher terrain./19

.LONG TERM...Tuesday Night through Sunday...A brief period of
dry conditions under shortwave ridging will keep the latter half
of Tuesday through Wednesday benign. The next potentially
impactful system is expected to impact the region late Wednesday
night into Thursday, though there is substantial differences
among the models and their ensembles. Cluster analysis remains
split between solutions with around 35% showing a weak trough,
34% showing a much deeper trough with an amplified pattern, 16%
close to zonal, and the last 15% with a deeper trough but well
offshore. Deterministic models show plenty of disagreement in
the overall progression of the trough. The GFS leans towards a
similar pattern with the trough base pinching off and dropping
southeast, leaving northwest OR and southwest WA in a region of
weaker forcing. THe EURO on the other hand, keeps the trough
intact through its eastward progression, leading to better
forcing, higher precipitation totals and a better chance for
mountain snow. Depending on what happens with this late week
system, could see impactful snow around the mountain passes
though, NBM spread is quite large with some showing no snow and
others showing 6 inches or more. Chances for 6 inches of snow
Thursday through Friday at the Cascade passes is a mere 5%. Will
need to keep an eye on this system as it approaches late next
week. /19

&&

.AVIATION...A frontal system continues to progress through the
region and is resulting in a widespread mixture of flight
conditions across the air-space. Precipitation will remain in the
forecast through the TAF period, but can`t rule out some brief
breaks in the precipitation through the TAF period. It should be
noted that poor model performance today and the tendency for the
lower cloud decks to linger this time of year, forecast confidence
going forward is low in regards to the timing of any improvement
in flight conditions. Southerly winds inland will slowly join the
westerly winds already observed along the coast through the
overnight hours. After 15Z Monday, the frontal passages should be
well east of the region and as such, conditions are likely to
become a mixtures of low-end VFR/high-end MVFR, with the coast
likely (75-80% chance) leaning towards VFR, while inland areas are
expected (70-80% chance) leaning towards MVFR conditions. Light
shower activity expected to decrease through the day with
generally dry conditions expected after 00Z Tuesday.

KPDX AND APPROACHES...MVFR/IFR conditions expected to persist
along with light precipitation through the majority of the TAF
period. After 15Z Monday, the frontal passages should be
well east of the region and result in a mixture of low-end
VFR/high-end MVFR, with a higher potential (70-75% chance) of MVFR
conditions. /42

&&

.MARINE...A frontal boundary is progressing through the waters
this afternoon with southerly winds quickly shifting
northwesterly with gust up to 18-25 knots by the evening hours.
This frontal feature will also support seas building to 10-14 ft
at 13-14 seconds, likely lasting through most of Monday - a
Small Craft Advisory remains in effect into Monday evening.
After this point seas are expect to fall back into the 6-8 ft
range at 11-12 seconds for Tuesday. Lighter west-northwest winds
return Monday night into Tuesday as well. Looking ahead, after
the continuation of fairly benign winds/wave heights by late
fall standards through most of Wednesday, yet another frontal
system pushes into the waters late Wednesday into Thursday. As a
result, wind gusts likely increase into the 20-30 knot range
with a mature swell building seas into at least mid teens. The
GEFs projects a 50-70% chance for wave heights to exceed 15 ft
but there is also a 10-25% chance of 20 ft seas or higher. An
active weather pattern likely continues into the weekend. -99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 7 PM PST Monday for PZZ210.

     Small Craft Advisory until 10 PM PST Monday for PZZ251>253-
     271>273.
&&

$$

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