401
FXUS66 KPQR 291821
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1120 AM PDT Wed Jul 29 2026

...Updated aviation discussion...

&&

.SYNOPSIS...Onshore flow persists through much of the next
week, while high pressure building offshore will see
temperatures trend warmer through Friday. A frontal system
Saturday will bring the next chances for light rain and usher in
a broad pattern change this weekend into next week.

&&

.SHORT TERM...Now through Friday...Broad upper-level ridging
currently centered over the Rockies will build and retrograde
westward over the Great Basin through Friday, increasing heights
aloft locally and supporting a warming trend across the region.
Temperatures near normal in the mid 60s on the coast and low
80s within inland valleys are expected today and tomorrow as
weak waves within the southwesterly flow aloft will keep heat
from rising to hazardous levels. Even on Friday, temperatures
will most likely peak in the mid 60s to low 70s at the coast and
mid to upper 80s inland, supporting generally Minor HeatRisk.
The warmest locations with the highest chance (25-45%) of
reaching Moderate HeatRisk will be the Tualatin Valley.
Otherwise, a typical summertime pattern will see dry weather and
morning clouds, especially along the coast, clearing to mostly
sunny skies each afternoon.      -36

&&

.LONG TERM...Friday Night through Tuesday...A more substantial
pattern shift will begin Friday night into Saturday as an upper
trough moves from the Gulf of Alaska inland over the Pacific
Northwest. This system will bring a cold front into the coast on
Saturday. Rain may begin along the southern Washington and far
northern Oregon coasts as early as Friday night, but is most
likely on Saturday morning. The highest chances for rainfall of
0.01 inches or more are 35-55% along the coast and coastal
terrain north of Florence with the odds increasing to the north,
as well as along the Cascades north OR-22 (or from the Marion-
Linn County line northward). Any rainfall will most likely be
very light, amounting to no more than 0.05-0.10 inches. Near to
slightly below normal high temperatures in the 60s and 70s are
expected through the weekend in the wake of the frontal passage.

As the progressive upper trough exits eastward, there is
increased uncertainty in the evolution of the pattern by early
next week. Long-range ensembles depict a high probability of
strong upper-level ridging developing over the Four Corners, but
whether that will translate to hot weather locally is more
uncertain. While warmer temperatures compared to the weekend are
all but certain, the spread of potential solutions remains wide;
a best forecast at this lead time is for afternoon highs in the
70s along the coast and upper 80s to low 90s inland, however
there is a 25% chance high fail to reach even 85 degrees inland,
as well as a 25% chance of reaching 95 degrees on Tuesday and
Wednesday within the Willamette Valley.      -36

&&

.AVIATION...Through 18z Thursday...Satellite imagery as of late
Wednesday morning shows stratus quickly dissipating across the
Willamette Valley as mixing increases from daytime heating. Expect
predominately VFR conditions through the TAF period for Valley
terminals with FEW/SCT high clouds (>25 kft) at times. There is a 20-
30% chance for MVFR stratus re-developing across Valley terminals at
any given hour between 10-17z Thu as the low level atmosphere
moistens overnight. Along the coast, will also see stratus breaking
up and conditions improving to VFR this afternoon. After 06-07z Thu,
there is high confidence for low-end MVFR stratus (1-2 kft)
returning along the coast and persisting through Thursday morning.
Northwesterly winds 5-10 kt today, strongest in the afternoon with
gusts up to 20 kt along the coast.
Winds ease overnight.

KPDX AND APPROACHES...VFR conditions through the TAF period with
high clouds. 20-30% chance for MVFR CIGs at any given hour between
10-17z Thu. Northwesterly winds 6-8 kt today, weakening under 5 kt
tonight.      -10

&&

.MARINE...Buoy observations from early Wednesday morning show
seas continuing at 4-6 ft, which are expected to persist through
much of the week with a dominant west to northwest swell at 7-9
seconds and a secondary long-period south-southwesterly swell.
A frontal system approaching the waters late this week will see
northerly flow back ahead of the weak surface front beginning
Thursday. Chances for light rain peak late Friday night into
Saturday morning during the frontal passage.

Behind the boundary, initial westerly flow will veer out of the
north through the weekend as surface high pressure builds
offshore. Chances for maximum wind gusts of at least 20-25 kt
peaks at 85-95% across the waters from Sunday through at least
Tuesday, with the highest chances off the central Oregon coast.
Chances that peak afternoon gusts reach gale-force is the
highest on Monday afternoon, some 30-50% within 10 NM south of
Cape Falcon and 25-45% beyond 10 NM. Chances for gale-force
gusts north of Cape Falcon are lower, only 5-20%.      -36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

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