149
FXUS66 KPQR 021729
AFDPQR

Area Forecast Discussion...Updated Aviation
National Weather Service Portland OR
1004 AM PDT Wed Jul 2 2025

.SYNOPSIS...Onshore flow returns today which will bring in
cooler and more moist air. Stronger westerly flow will cause
winds to increase in the Columbia River Gorge and Upper Hood
River Valley through today.

&&

.SHORT TERM...Now through Friday...The upper level ridge which
brought high temperatures into the 90s is beginning to decay.
This will initiation the return of onshore flow and cooling
temperatures through the rest of the week. Overall, 850 mb
temperatures will fall to around 10 degrees C each day. There
will be a drastic drop in temperature today with highs only
forecast to reach 80 degrees in the Greater Portland-Vancouver
Metro 80-85 degrees in the southern Willamette Valley from
Corvallis South, in the low 80s through the Gorge, and 60s along
the coast. For those still dreaming of temperatures in the 90s,
you better head to the east as there is less than a 5% chance
anywhere in the forecast area.

On Thursday into Friday a weak shortwave aloft will move over
the area. This will increase some convective behavior though
thunderstorms are not necessarily expected. However, some
showers are possible over the Lane County Cascades. As it passes
could see an increase of westerly winds through the passes,
though not expected to be impactful.

For those wanting to enjoy outdoor activities on the 4th,
prepare for seasonable temperatures, mostly clear skies, and no
rain.
  -Muessle

.LONG TERM...Friday Night through Tuesday...The trough continues
to push inland through the weekend and ridging builds in behind
it. Will see a return of warmer conditions though flow will
continue to be onshore aloft. Therefore, conditions not expected
to be exceptionally warm until late in the forecast on Monday or
Tuesday. As we round out the weekend, flow will shift to the
north-northeast ushering in much drier and warmer air to the
region. A weak thermal trough will begin to form on Sunday
afternoon. At this point, the pressure gradient, combined with
the temperature gradient across the Cascades, will intensify.
Westerly winds will ramp up late Sunday afternoon.

500 mb height ensembles are in fairly good agreement moving
forward with the ridge intensifying. Temperatures will rise by
around 5 degrees each day on Monday and Tuesday with around a
50% chance of exceeding 90 degrees on Monday through the
Willamette Valley, and 75% or more on Tuesday.-Muessle


&&

.AVIATION...Marine stratus clouds continuing to impact the
north Oregon/southern Washington coast, as well as the northern
Willamette Valley. Clearing has been relatively slow, and MVFR
conditions with a deck around 1500 ft expected to continue until
18-20z Wed. Afterwards, clearing to VFR for inland terminals.
Coastal terminals likely see intermittent MVFR conditions at times
throughout the duration of the period. Winds expected to pick up
Wednesday afternoon around 22z Wed, with northwesterly gusts up to
15-20 kts possible for all terminals. These will drop below 10 kt
by 4z Thu or so.

PDX AND APPROACHES...Continued broken deck of marine stratus
clouds around 2000 ft AGL. This deck is currently in the process
of breaking up, and expecting this to clear to a scattered deck of
clouds by 20z Wed at latest. Afterwards, VFR throughout the
period. Gusts of up to 18-20 kts are possible Wednesday afternoon
from 22z Wed to around 5z Thu. Winds below 8 kts afterwards. /JLiu

&&

.MARINE...Persistent surface high pressure offshore will result in
continued north to northwesterly winds across the waters. Diurnal
gusts will reach 10-15 kt north of Cape Falcon and 15-20 kt from
Cape Falcon to Florence each afternoon, easing to around 10 kt
overnight. Seas will continue at 3-6 ft through the weekend.
Strengthening surface high pressure will then see winds and seas
build Sunday into next week. -Picard

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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