436 
FXUS66 KPQR 281753
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1053 AM PDT Sun Sep 28 2025

Updated Aviation & Marine discussions and WWA...

&&

.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 continue inland beneath increasing 
high cloud coverage. MVFR stratus in the southern Willamette 
Valley including at KEUG is expected to erode by 20-21z Sun, 
giving way to VFR conditions through the afternoon and evening.
Along the coast, more persistent MVFR cigs are expected, however 
intermittent IFR cannot be ruled out at KONP through 20-21z Sun. 
Winds will continue generally out of the south throughout the 
period ahead of an approaching cold front, with gusts of 20-25 kt
are likely at coastal terminals through much of the period. A few
breaks to VFR are also possible at the coast near 00z Mon, but 
confidence in occurrence and timing remains low. Rain arrives and 
stalls along the coast by 09-12z Mon, not pushing inland until 
closer to 12-15z Mon or later, bringing largely MVFR cigs/vis.

KPDX AND APPROACHES...VFR conditions expected through the period
with increasing high clouds ahead of an approaching cold front.
Southerly flow at 5-10 kt will continue, while rain showers may
begin to arrive by 12-15z Mon as cigs fall to low-end VFR. Chances
for MVFR cigs increase after 18z Mon as the front arrives. -Picard

&&

.MARINE...Update: visibility has improved above 1SM and the 
Dense Fog Advisory across the waters has therefore been
cancelled. See previous discussion below. -Picard

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.

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...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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