576 
FXUS66 KPQR 030611 AAC
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1108 PM PDT Thu Oct 2 2025

.SYNOPSIS...Dry and seasonable on Friday with northerly flow aloft.
Light rain showers likely on Saturday, especially in the morning.
Low-level offshore flow develops Sunday and continues through at
least Tuesday, bringing an extended period of dry weather with
daytime high temperatures in the 70s across the lowlands.

&&

.DISCUSSION...Thursday night through Wednesday night...Scattered rain
showers continue to be observed across northwest Oregon and southwest
Washington, but will begin dissipating after sunset. Dry northerly
flow aloft and high pressure at the surface develops on Friday,
bringing dry weather with seasonable high temperatures in the 60s.
Winds look fairly light on Friday, around 5-10 mph or less.

Chances for rain have increased considerably on Saturday, with
probabilities now peaking between 50-80%. This is in response to a
series of two upper level impulses embedded in northerly to
northwesterly flow aloft that will move southward over the forecast
area. The first impulse moves through during the early morning,
bringing a brief period of light rain to most locations. The second
impulse moves through during the afternoon and early evening,
resulting in isolated light rain showers. Although PoPs are high,
forecast rain amounts are low, ranging from a trace to a few
hundredths of an inch.

The forecast remains dry Sunday through Wednesday in response to a
prolonged period of offshore flow. This pattern change will result in
mostly sunny and breezy conditions with temperatures becoming
noticeably warmer. Expect highs temperatures in the 70s each day
across the lowlands. Even the coast will likely warm into the 70s on
Monday and Tuesday due to easterly winds downsloping on the lee side
of the coastal mountains, resulting in compressional warming and a
lack of cloud cover. Tuesday is shaping up to be the warmest day of
the week with highs well into the 70s. Probabilities for highs of 80
degrees or warmer are low, ranging between 5-10%.

Lastly, overnight lows in the Upper Hood River Valley near Parkdale 
will likely fall into the upper 30s on Friday morning. Cannot
completely rule out patchy frost Friday morning given the clear skies
and light winds in place, however the probability for this to occur
is at 10-30% across the Upper Hood River Valley, except 50% in
Parkdale. Given the marginal temperatures in place and the fact that
temperatures will most likely stay above 36-37 degrees, have decided
not to issue a Frost Advisory. However, given that it is now October,
the climatological likelihood of frost developing is increasing. -59

&&

.AVIATION...Rain has mostly dissipated, resulting in mostly VFR
conditions throughout the airspace. A few terminals inland currently
under MVFR conditions should improve to VFR by 06Z Friday. The
coast will be an exception, with southerly wind bringing cool and
moist air into the area, improving the chances for fog and low 
stratus. With clear conditions and residual moisture from recent
recent, there is low to moderate confidence for fog/stratus
development overnight. Specifically, there is a 30-50% chance of 
LIFR/IFR conditions from now until 16-18Z Friday (highest chances 
at KONP). While guidance does suggest a 10-20% chance for
fog overnight, lingering cloud cover will likely prevent 
radiational cooling, therefore preventing fog development. Still,
there is a 30-60% chance for MVFR conditions from between 11-18Z
Friday for inland terminals (lowest to highest chances from north
to south). Otherwise, winds will stay light and variable through
the TAF period. 

KPDX AND APPROACHES...VFR conditions through most of the TAF 
period. The only exception is a 20-30% chance of MVFR 
conditions between 11-17Z Friday. Cloud cover will likely persist
long enough to inhibit fog development. Otherwise, light and
variable winds. 
-12

&&

.MARINE...Seas around 8-10 ft will continue to decrease overnight
into Friday, decreasing to around 5-7 ft by mid Friday. On 
Saturday winds will begin to shift to the west before becoming 
northerly in the afternoon as another weak front moves into the 
area. Winds will increase through Sunday with a high probability 
(greater than 50% chance) of Small Craft Advisory winds in the 
outer waters late into Monday morning. Ridging follows. -12/27

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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