200
FXUS66 KPQR 301120
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
420 AM PDT Thu Jul 30 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 favoring warmer weather into next week.

&&

.SHORT TERM...Now through Friday Night...Broad upper-level
ridging centered over the Rockies will continue to build and
retrograde westward over the Great Basin through Friday,
increasing heights aloft locally and supporting a warming trend
across the region. Near normal temperatures in the mid 60s on
the coast and low 80s within inland valleys are expected today
as weak waves within the southwesterly flow aloft will keep heat
from rising to hazardous levels. Even on Friday, while still
expected to be the warmest day of the week, temperatures will
most likely peak in the mid 60s to low 70s at the coast and mid
to upper 80s inland. These conditions are not atypical for this
time of year, and will support only Minor HeatRisk. 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...Saturday through Wednesday...A more substantial
pattern shift will be underway by Saturday morning 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. Chances for rain peak during the day on Saturday, most
notably along the coast and within coastal terrain, as well as
inland to the north of Portland. There are 50% or greater
chances of accumulating (0.01 inches or more) rain from Newport
northward on the coast, and 80-90% chances from Tillamook north
through the Long Beach Peninsula. Inland, the probability of
accumulating rain rises from only 5% in Portland to 55-65% in
the Lewis and Cowlitz Valleys. Rainfall amounts are very likely
to be 0.05-0.10 inches or less, with only a 10% chance of seeing
0.20 inches in coastal Clatsop and Pacific Counties. During and
behind the frontal passage, below normal high temperatures in
the low to mid 60s along the coast and mid to upper 70s inland
are expected through the weekend.

As the progressive upper trough exits eastward, there is higher
uncertainty in the evolution of the pattern by early next week.
Long-range ensembles depict a high probability of strong upper
ridging developing over the Four Corners, but whether that will
translate to hot weather locally is lower confidence. While
temperatures are very likely to be warmer compared to the
weekend, the spread of potential solutions remains somewhat
wide. At this point, there is an 80% chance of highs in the 80s
within inland valleys on Monday and a 75% chance of reaching
the 90s on Tuesday, before the potential envelope of outcomes
widens substantially on Wednesday, when highs anywhere in the
80s or 90s remain possible. In the warmer solutions, inland
ridging and resultant coastal thermal troughing may be
sufficient to drive periods of offshore flow, resulting in
potential gusty north winds along the coast and within the
Willamette Valley. -36

&&

.AVIATION...Through 12z Friday...Largely VFR flying conditions
continue early this morning with scattered low clouds across the
airspace per latest satellite imagery. Terminal observations
have shown intermittent MVFR cigs along the coast, and have
maintained TEMPO groups given low stratus coverage expected to
persist through much of the morning (16-18z Thu) and short-range
guidance continuing to favor 60-80% probabilities of at least
bkn cloud cover below 3 kft. At inland terminals, confidence in
cloud bases below 3 kft is lower (30-40%), except within the
southern Willamette Valley including KEUG where chances for MVFR
cigs are just over 50% through much of the morning. Where cloud
breaks are more widespread, there are low (<10%) chances for
fog development yielding IFR/LIFR cigs, and have only included
vis restrictions at KSLE where LIFR vis has already been
observed. Low clouds will tend to mix out by 16-18z, returning
conditions to VFR across the region. Light winds this morning
will build to 5-10 kt out of the north to northwest by this
afternoon, then ease below 5 kt after 04-08z Fri.

KPDX AND APPROACHES...VFR conditions likely throughout the
period. Low to moderate (30%) chances of MVFR cigs this
morning if stratus coverage increases, with skies clearing by
this afternoon. Diurnal northwest winds expected to rise to
around 5 kt by 18z Thu, then ease after 06-08z Fri. -36

&&

.MARINE...Buoy observations continue show seas of 4-5 ft early
Thursday morning, 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. Backing
winds are expected today ahead of a frontal system approaching
the waters Friday into Saturday, mainly for the waters north of
Cape Falcon and the waters beyond 30-40 NM south of Cape Falcon.
Chances for light rain peak Saturday morning during the frontal
passage, with 10% or less chances of rain beginning before dawn.

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
are greater than 90% across the waters from Sunday through at
least Tuesday. Chances that peak afternoon gusts reach gale-force
are the highest on Monday afternoon and increase to the south,
from less than 5% north of Cape Falcon to 35-50% south of Cape
Foulweather. -36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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