748
FXUS66 KPQR 261752 CCA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1052 AM PDT Thu Jun 26 2025

.SYNOPSIS...Onshore flow will maintain cloudier weather and more
seasonable to slightly below normal temperatures through Friday.
Areas of light drizzle will remain possible later this morning
along the coast and for inland areas north of Salem. Warm and
dry conditions return this weekend into early next week with
inland high temperatures approaching or exceeding 90 degrees in
many locations Sunday and Monday.

&&

.SHORT TERM...Now through Friday Night...Water vapor imagery
shows little change in the upper level pattern this morning as
longwave troughing spanning from the Gulf of Alaska into western
Canada keeps robust onshore flow focused over the Pacific
Northwest. This pattern maintains extensive cloud cover west of
the Cascades, with the vertical wind profiler at KAST showing a
marine layer depth of around 3000 ft as of 3 AM Thursday. Not
currently seeing any precipitation being reported around the
region, but expect another round of light rain/drizzle to
develop later this morning as the latest disturbance approaches
from offshore and provides some weak forcing, lingering into
the afternoon across parts of southwest Washington. Once again
do not expect more than a trace to a couple hundredths of an
inch of precipitation through this evening, with areas along the
northern coast from Astoria to Long Beach showing a 10-15%
chance to receive as much as a tenth of an inch of rain today.
Any precipitation inland should largely be limited to areas
from Portland northward as the central and south Willamette
Valley remain dry. Much like Wednesday, expect that extensive
cloud cover will again keep temperatures this afternoon a
couple degrees below guidance as highs top out around 70 degrees
in the Willamette Valley and closer to the upper 60s across
southwest Washington.

Onshore flow will maintain similar conditions on Friday, except
with any light rain or drizzle mostly staying confined to
southwest Washington. Clouds will also have the potential to
scatter out a bit more during the afternoon, allowing highs to
end up closer to the low to mid 70s in the Willamette Valley
while marine influences keep coastal communities down in the 60s
for another day. Onshore flow will also maintain breezy west
winds through the central Columbia River Gorge each afternoon
as winds gust to 25-30 mph in some spots around Hood River. /CB

.LONG TERM...Saturday through Wednesday... A stretch of warmer,
drier, and sunnier weather will commence on Saturday as models
continue to depict a building upper level ridge over the western
CONUS with a cutoff low developing over the California coast.
Increasing 500 mb heights will allow temperatures to jump back
up into the low 80s in the inland valleys on Saturday.
Temperatures still look to peak Sunday into Monday as the ridge
continues to amplify, with the NBM now depicting a 50-70%
chance to reach 90 degrees in the Willamette Valley on Sunday
and a 75-90% chance on Monday. Locations across interior
southwest Washington show notably lower probabilities to reach
90 degrees, with highs in the 80s more likely from Kelso through
the Cowlitz Valley. Probs to reach 95 degrees have backed off
somewhat for Monday, now sitting closer to 15-35% in most
locations in the Willamette Valley. The mid 90s continue to
represent a reasonable worst case scenario for heat on Monday
as the chance to reach 100 degrees continues to reside in the
low single digits. Temperatures look to level off somewhat
beyond Monday, but will still remain well above normal as
guidance keeps highs in the 80s for much of the rest of the
week, showing around a 30-40% to reach as high as 90 degrees for
Tuesday and Wednesday.

The other forecast concern in the long term will be the
potential for thunderstorms along the Cascades during the first
half of next week, which will largely be dependent upon the
evolution of the aforementioned cutoff low near the California
coast. This will have the potential to draw monsoonal mid level
moisture northward into our area in southeast flow aloft, which
is often challenging for the NBM to resolve. A farther north
position of the low will generally be more favorable for
thunderstorms to reach into the central and northern Oregon
Cascades. For now, will maintain a 15-20% chance of
thunderstorms along parts of the Cascades both Monday and
Tuesday afternoon, but will need to keep a close eye on how this
pattern evolves in the coming days. /CB

&&

.AVIATION...Onshore flow with marine stratus. Radar shows isolated
showers in the area but due to the dry lower atmosphere, rain is not
reaching the ground. Biggest concern in regards to CIGs. The
southern portions of the area (south of KSLE) are beginning to clear
and will continue to do so over the next few hours. The northern
portions will likely back build off of the Cascades.
Could see some partial clearing around KHIO but confidence is low in
significant clearing. A weak front will pass over the area again on
Friday maintaining similar conditions.

PDX AND APPROACHES...MVFR CIGs through the early afternoon will
slowly lift to VFR after 20Z Thu with a scattered deck in the 2000
ft range. Winds will be northwesterly. Saturation will once again
cause CIGs to lower once again to high end MVFR levels. -Muessle

&&

.MARINE...A series of weak fronts will pass over the waters
through the remainder of the week which will maintain generally
westerly winds along with seas less than 6 ft. Each weak frontal
passage will result in a brief southerly wind shift. However, over
the weekend, as high pressure develops expect a northerly wind
shift as is typical with our summer time patterns. Also, winds
will begin to ramp up with a 75-90% probability of Small Craft
Winds across all waters. Seas too will respond with general seas
around 3-5 ft at 8-10 seconds with seas building towards 4-7 ft
by this weekend and into the start of the upcoming week.
/42-Muessle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&

$$

www.weather.gov/portland

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