Mt. Bachelor

000
FXUS66 KPQR 281135
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
435 AM PDT Tue Jul 28 2026

Updated aviation discussion.

&&

.SYNOPSIS...Persistent onshore flow will bring near-average 
temperatures with varying degrees of morning clouds and 
afternoon sunshine for much of the next week. A series of weak 
fronts will bring notable chances for light rain and drizzle to 
portions of the Washington and north Oregon coasts today and 
this weekend, while Friday is likely to be the warmest day.

&&

.DISCUSSION...Now through Monday...The large-scale pattern will
remain fairly steady through the next week with the region
wedged between upper-level troughing over the Gulf of Alaska and
upper-level ridging over the Rockies and Central Plains. In
general, the weather locally will be typical for the mid-summer:
morning clouds followed by increasing afternoon sunshine,
seasonable temperatures, and largely dry conditions, but with
some variations as the relative strengths of these two dominant
features change.

Today, an upper shortwave passing to the north will tilt the 
scales in favor of upper troughing, sending front toward the 
coast resulting in slightly below normal temperatures across the
region, namely afternoon highs in the low to mid 60s at the 
coast and upper 70s to low 80s within inland valleys, as well as
chances for light rain or drizzle along the northern Oregon and
southern Washington coasts and within coastal terrain. Chances 
for accumulating rainfall (0.01 inches or more) are less than 
10% in Lincoln and Lane Counties, 20-40% in Tillamook and 
Clatsop Counties, and 50-80% in Pacific County. Inland, chances 
are lower, only 5-25% from the Portland metro north into the 
Lower Columbia and Cowlitz Valleys.

Wednesday through Friday, the upper-level ridge will strengthen
and retrograde westward into the Great Basin, increasing 
heights aloft locally and tipping the balance toward warmer and 
drier weather. Continued onshore flow will limit the likelihood
of hazardous heat, but except above-normal high temperatures
most likely in the upper 60s to low 70s along the coast and in
the mid to upper 80s within inland valleys by Friday. These
temperatures result in only Minor HeatRisk across the region,
with the chances for Moderate HeatRisk of around 5% along most
of the I-5 corridor except 15-45% in the Portland/Vancouver
metro, highest in the Tualatin Valley.

By the weekend, there is higher uncertainty in the evolution of
the upper-level pattern, but many ensemble members depict more
pronounced troughing returning to the Pacific Northwest,
favoring cooler temperatures and further chances for rainfall.
At this time, rain chances peak on Saturday along the coast and
especially from Lincoln City northward. -36

&&

.AVIATION...Through 12z Wednesday...Latest satellite depicts 
marine stratus entrenched along the coast and beginning to
slowly  push inland as a weak front traverses the coastal 
waters. MVFR cigs at coastal terminals are likely to remain in 
place through the morning, with modest 30-60% chances of falling
to IFR levels by 15z Tue as winds turn onshore, before lifting 
through the afternoon. Light rain showers are most likely along 
the south WA and far north OR coasts through the mid-afternoon, 
but terminal impacts are unlikely beyond lowered cigs. Southwest
winds rising to 8-12 kt with gusts of 15-20 kt at KAST ahead of
the boundary will veer out of the northwest following the 
frontal passage. Chances increase after 03z Wed for further 
marine stratus.

At inland terminals, largely VFR conditions are expected through 
the period. MVFR cigs are most likely (60% chance) at KPDX/KTTD 
and KEUG after 14-15z Tue as marine stratus makes its way inland
through gaps in the coastal terrain. At other terminals, cloud 
bases above 3 kft remain favored with 30-40% chances of MVFR 
cigs after 14-15z Tue. Low clouds will tend to mix out by 18-20z
Tue. Light southerly winds this morning will rise to 5-10 kt 
and veer out of the southwest ahead of the boundary, then veer 
further to the northwest or north following the frontal passage.

KPDX AND APPROACHES...Moderate confidence (60% chance) that VFR 
conditions degrade to MVFR by 14-15z Tue as low marine stratus 
encroaches inland along the Columbia River, with low clouds then
tending to mix out by 18-20z Tue. VFR conditions otherwise 
prevail as light southerly winds rise to 5-10 kt out of the 
southwest by midday, then turn northwesterly behind the frontal 
passage this evening. -36

&&

.MARINE...Seas of 4-5 ft per buoy observations are expected to 
continue with a dominant west to northwest swell at 8-9 seconds 
and a secondary long-period south-southwesterly swell persisting
through much of the week. Light southerly winds early this 
morning will build and veer out of the north to northwest by 
this evening behind a weak frontal boundary. Maximum gusts will 
most likely remain in the 15-20 kt range, however intermittent 
or isolated gusts to 25 kt may occur during the frontal passage,
most likely to the north of Cape Falcon. More typical 
summertime northerlies will then continue through the remainder 
of the workweek.

Another weak front looks to traverse the waters early this
weekend, after which northwesterly flow will strengthen and
veer out of north into early next week as high pressure builds
offshore. Confidence in wind gusts of at least 20-25 kt is
moderate to high on Sunday, increasing from around 60% west of
the mouth of the Columbia to greater than 90% offshore of
Florence. Those chances are even higher on Monday, some 90-95%
or higher across the coastal waters. The chances for gale-force
gusts on Monday are low but not negligible, generally 10-20% 
south of Cape Foulweather as well as within 10 NM of the coast 
from Cape Falcon to Cape Foulweather. -36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

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