970
FXUS66 KPQR 150543 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
944 PM PST Fri Nov 14 2025

Updated Aviation and Marine Discussion...

.SYNOPSIS...Zonal flow through the weekend will transition into
a long wave trough with a closed low over northern California.
Will see a steady cool down but not a cold snap. Rain and
mountain snow expected. Another round of cold and moist air
occurs on Thursday through Friday though conditions have warmed
slightly since previous forecasts.

&&

.SHORT TERM...Now through Saturday Night...Satellite shows
generally zonal flow over the region with a broad area of low
pressure sitting within the Pacific. Westerly flow will
instigate showery conditions which are producing locally heavy
yet non-impactful accumulations. On Saturday, weak upper-level
ridging will begin to develop east of the Cascades, lowering the
chances for additional rain inland. Inland locations will see
around a 20-30% chance of accumulating rainfall (0.01" or
greater), while the coast will be closer to 50%. Daytime high
temperatures will reach their peak on Saturday. One slight shift
on Saturday night into Sunday will be the potential for fog
development. If enough clearing occurs overnight, fog within the
Coast Range valleys will form. Inland sites may remain too dry
for that to occur, however, our more fog prone areas like around
Eugene or Hillsboro may see some patchy fog. -27


.LONG TERM...Sunday through Friday...The ridging will begin to
break down on Sunday as a long wave trough associated with a
broad low pressure system to the north advects southward. The
main impacts from this system will occur on Monday through
Tuesday. Unfortunately this trough has yet to come into good
agreement and that is due to it`s split nature. Some models are
suggesting a closed low forming near the base of the trough
while others are keeping it as one "solid piece". Let`s look at
each possible solution and what the impacts would be.

If the closed low theory takes hold, the most likely track is
again over northern California. The low itself would be active
and would advect colder air over the region. The colder air and
more active pattern would promote heavier precipitation and
likely lower snow levels. If a more elongated low manifests
then the cold air intrusion will be less robust and thus snow
levels slightly lower. While the pattern may have much to be
desired for consistency, the sensible weather has not be
effected significantly. Over the last few forecasts snow levels
have continued to rise with lower and lower probability for
advisory level snow (6-12"). On Monday through Tuesday there is
less than a 10% chance of pass level advisory level snow, and
less than a 20% chance of volcano heavy snow accumulation.

On Wednesday, an inverted trough forms as the upper level low
moves into the desert southwest. Fast forward to Thursday and
Friday. This is when yet another fall system will move in. In
current ensembles there is basically no agreement in specifics
and anomaly is high in the 500 mb heights. There continues to
be a low attempting to form just off the coast but once again,
poorly realized. Currently the ECMWF is the coldest of the
modeled ensembles while the GEPS is much warmer. With that in
mind, probabilistically we are all over the place. For example,
at Willamette Pass there is around a 25% chance of 6" or more
of snow. There is high consensus in overall temperatures
lowering on Wednesday and Thursday. -27


&&

.AVIATION...Currently, VFR conditions throughout most of the
interior valley, with MVFR conditions along the coast as of 05Z
Saturday. Expect conditions to degrade overnight as a front moves
through. Along the coast, MVFR conditions will degrade to IFR
conditions around 08-12Z Saturday, with guidance suggesting a
30-50% chance of IFR conditions through the rest of the TAF
period (highest chances to the north). For most terminals inland,
VFR conditions will degrade to MVFR conditions around 08-12Z
Saturday and persist through at least 00Z Sunday. Guidance
suggests a 40-70% chance for MVFR conditions, with a 10-20% chance
for IFR conditions at a few terminals between 12-22Z Saturday.
KEUG conditions look to be more favorable towards VFR conditions,
with only a 15-25% chance of MVFR conditions.

Otherwise, expect light rain to become more widespread and
steadier by 08Z Saturday, but still mostly kept out of the
southern Willamette Valley. Precipitation will then gradually
decrease through Saturday morning. Winds will stay breezy at most
terminals tonight, with occasional gusts up to 15 to 25 knots out
of the south, highest at coastal sites. Winds will begin to weaken
around 12Z Saturday.

KPDX AND APPROACHES...Light rain will become steadier tonight
around 08Z Saturday with CIGs dropping to a prevailing MVFR.
Light rain will slowly ends around 16-18Z Sat before dry weather
returns. There will still be a 30-50% chance for MVFR CIGs through
at least 06Z Sunday.
~12

&&

.MARINE...Seas continue to remain around 9-10 ft and winds gusting
to around 20-25 kt. In response to these conditions persisting,
the Small Craft Advisory has been extended until 3 AM Saturday.
Expect seas to subside to 6-8 ft through Saturday and Saturday
night, with winds gusting under 20 knots.

Another frontal system traverses the waters Sunday into Monday,
bringing increased southwesterly winds with gusts to 15-21 knots
before turning out of the northwest. A westerly swell helps to
increase wave heights to 13-15 ft on Monday morning as well,
before falling below 10 ft again on Tuesday. Should this forecast
remain on track, an additional round of Small Craft Advisories
will be needed for the inner and outer waters. Expect a fairly
active and progressive weather pattern to continue the rest of the
week as yet another weather system may bring hazardous winds and
seas later in the next week. Models show a 30-50% chance for wave
heights to meet or exceed 15 ft on Thursday.
~12/99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 3 AM PST Saturday for PZZ210-251-252-
     271-272.
&&

$$

www.weather.gov/portland

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