487 
FXUS66 KPQR 281024
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
324 AM PDT Sun Sep 28 2025

.SYNOPSIS...Dry conditions become wet and cool for the work 
week. Multiple frontal systems will bring periods of widespread
rain and breezy winds to the region. The first will be Monday, 
followed by the strongest system Tuesday through Wednesday, with
unsettled conditions continuing through Friday.

&&

.DISCUSSION...Sunday through Saturday...Dry and mild weather 
will transition to a wet and cool pattern through today with 
inland high temperatures in the upper 60s to upper 70s. A 
significant pattern change is on deck for the PacNW as a series
of frontal systems associated with an upper level parent low in
the NE Pacific Ocean will send a series of fronts into the
region resulting in periods of widespread rain through the work
week. 

The first front is expected today and will bring increasing 
clouds, southerly winds with precipitation by tonight/early 
Monday morning. Breezy southerly winds are expected along the 
coast with gusts up to 30 mph starting this afternoon through 
early Monday morning. This will be a relatively quick-moving 
system with stratiform rain this evening turning to scattered 
showers by Monday morning. Rain amounts suggests 0.40"-0.80" 
along the Coast and Coast Range, 0.25"-0.50" along the 
Cascades, and 0.10-0.40" for inland valleys. 

The next frontal system is still expected to be stronger than 
the first, impacting the region Tuesday into Wednesday. Winds 
could be more impactful with this front, especially along the 
coast. NBM indicates anywhere from a 25-50% chance of wind gusts
reaching at least 50 mph along the coast within a 24 hour 
period ending 11 PM Tuesday. However, significant spread exists 
within GFS, Euro, and Canadian ensemble members on strength of 
the winds with a more likely scenario being widespread gusts of 
35-45 mph with maybe a few isolated gusts of 50-55 mph. Some 
timing uncertainties continue, as well, but generally expect 
winds to increase along the coast Tuesday afternoon through 
Wednesday morning, peaking late Tuesday afternoon through the 
evening. Winds inland don't look strong at this point with only 
a 5-10% chance of gusts reaching 40 mph in the valley. Best 
chances are for gusts up to 25 mph, locally up to 30 mph as the 
front passes. Another widespread band of rain will move through 
the area Tuesday afternoon/evening through early Wednesday, with
showers continuing through the day Wednesday as well as an 
increasing chance (15-25%) of post-frontal thunderstorms in the 
afternoon. Rain amounts are expected to be higher with this 
system than the first one. Rain amounts with system range from 
0.60"-1.00" along the Coast and Coast Range, 0.30"-0.80" along 
the Cascades, and 0.30-0.50" for inland valleys. 

For Thursday into Friday, ensemble guidance remains in good 
agreement that the unsettled/active pattern will continue. 
However, uncertainty increases in specific details. The parent 
low pressure system looks to finally move onshore sometime 
Thursday into Friday, though there's quite a bit of spread as to
where this low will make landfall with models suggesting
landfall between the OR/CA border and the Olympic Peninsula. 
Given this uncertainty, rainfall totals for the latter part of 
this week are also varied. Latest ensemble means suggest another
0.50"-0.75" along the coast, 0.20"-0.70" for the Cascades and 
0.25-0.50" in for inland valleys. Given the cool and wet 
conditions on deck for this week, it looks like the death knell 
for the 2025 Fire Season might be struck. However, we won't 
really be able to call the season over until we see how much 
precipitation hit the ground.

Next weekend, looks to be on the dry side models having and
upper level ridge returning to the Pac NW. /42-HEC 

&&

.AVIATION...VFR conditions will persist for inland locations
through the majority of the TAF period. A moderate onshore push,
which will coincide with a weak frontal passage, could bring MVFR
conditions (20-30% probability) down the Columbia River towards 
KPDX around 14Z Sunday, with improvement back to VFR around 17Z 
Sunday. Marine stratus will remain well established along the 
coast and result in predominately IFR/LIFR conditions through the 
TAF. There could be brief periods of MVFR conditions at the coast,
but confidence in occurrence and timing is low, with the best 
opportunity for improved flight conditions from 21Z Sunday 
through 00Z Monday. Light to calm winds will become more southerly
ahead of the front, generally under 10 kt inland and 10-15 kt 
with gusts up to 25 kt along the coast.

KPDX AND APPROACHES...Predominately VFR conditions through the 
TAF period. A marine push could result in MVFR conditions (20-30% 
probability) impacting areas at or near the terminal starting 
around 14Z Sunday. Any lowered flight conditions at or near the 
terminal should improve back towards VFR around 17Z Sunday. Light 
and variable winds become southerly around 5-7 kt. /42

&&

.MARINE...A frontal passage today will increase southerly winds 
across all waters as well as result in building seas. Expect
southerly winds 10-20 kt with gusts up to 30 kt. Increasing to 
15-25 kt with gusts up to 30 kt. Along with isolated gusts up to 
35-40 kt, by late morning/early afternoon. Seas will also remain 
elevated in the 9-11 ft range with a dominant period of 12-14 
seconds. As a result of these conditions have issued a Small Craft
Advisory for all Waters to include the Columbia River bar through
tonight. As Monday approaches, winds are expected to fall below 
Small Craft criteria. Seas also are expected to subside towards 
7-9 ft.

Have also issued a dense fog advisory for all marine waters as 
dense fog will reduce visibility to 1 NM or less through this
afternoon.

Another, more potent frontal boundary will move into the waters 
late Monday night/Tuesday morning through Tuesday night. There is 
high confidence in widespread Gales across the waters, with 75-95%
chances of gusts up to 45 kt. Chances of storm-force gusts of 55 
kt or higher are around a 10-20% probability across the waters. 
Driven by strengthening winds, seas will quickly build toward 
15-19 ft, with a continued 10-20% chance of reaching 20 ft, 
especially beyond 30 NM. Seas look to slowly subside, but remain 
above 10 ft into the latter part of next week. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Dense Fog Advisory until 1 PM PDT this afternoon for PZZ210-
     251>253-271>273.

     Small Craft Advisory until 5 AM PDT Monday for PZZ210-251>253-
     271>273.

     Gale Watch from late Monday night through Wednesday morning for 
     PZZ210-251>253-271>273.

&&

$$

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