907
FXUS66 KPQR 090056
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
248 PM PDT Tue Jul 8 2025

.SYNOPSIS...Inland highs around 90 degrees again this afternoon.
A weak frontal system brings more seasonable temperatures for
Wednesday and Thursday, with a chance for some light rain along
northern coastal areas early Wednesday. Hotter temperatures
return Friday and persist into next week as strong high pressure
builds offshore.

&&

.SHORT TERM...Now through Thursday Night...High pressure remains
entrenched over the western CONUS today, promoting clear skies
across all of western Oregon and Washington with the exception
of some patchy marine stratus along the immediate coast.
Observations from around the area show highs in the upper 80s to
low 90s in the interior valleys as of mid afternoon. Visible
satellite shows cumulus fields starting to become more agitated
near and east of the Cascade crest in central Oregon, and expect
this to eventually yield a few thunderstorms this afternoon and
evening as cutoff upper level low pressure drifts inland from
northern California. Expect most of this activity to remain on
the east side of the Cascades, but will maintain a 15-20% chance
of thunderstorms along the Lane County Cascades this evening as
a few storms could move near the Crest later today.

A brief pattern change will commence tonight as a deep upper
level trough over the Gulf of Alaska pushes inland across
western Canada. This will send a weak surface cold front across
the Pacific northwest early Wednesday, bringing about cloudier
weather and more seasonable temps for the area Wednesday into
Thursday. Expect any precipitation chances to remain limited to
northern coastal areas and parts of southwest Washington on
Wednesday. Model QPF suggests parts of Pacific County could see
as much as a tenth or two of an inch of rain through early
Wednesday afternoon, but other locations along the north Oregon
Coast or the Cowlitz Valley will likely be limited to a trace
to a few hundredths. Although other locations are expected to
remain dry, passage of the front will at least bring some
temporary relief from the recent hot temperatures as afternoon
highs will run about 10 degrees cooler in the interior valleys,
maxing out in the upper 70s to around 80 degrees in most
locations. Expect dry weather on Thursday, with a bit less cloud
cover and temperatures rebounding by a few degrees into the low
80s in many interior locations. Meanwhile, persistent onshore
flow amd marine stratus will keep coastal temperatures in the
low to mid 60s going forward. /CB

.LONG TERM...Friday through Tuesday...Hotter temperatures return
on Friday and look to persist well into next week as ensemble
clusters remain in lock step in depicting a strong upper level
ridge developing across the NE Pacific in the long term. This
will likely correspond to a prolonged stretch of daytime highs
in the low 90s across the Willamette Valley and Portland
Vancouver Metro, helping to maintain a moderate Heat Risk in
these areas from Friday into next week. The probability to reach
95 degrees ranges from 60-80% from Salem to Eugene and 25-40%
in the Portland/Vancouver Metro each day from Friday through
Monday. The NBM is hinting at the possibility for even hotter
temperatures next Tuesday and Wednesday, with NBM 75th
percentile guidance depicting highs reaching the low 100s from
the Portland/Vancouver Metro to Eugene and pushing Heat Risk
into the Major category on Tuesday. It should be said that more
modest highs in the low 90s remain well within the range of
outcomes on these days, but the potential is there for the first
widespread triple digit readings of the summer as we head into
Tuesday and the middle of next week.

In terms of precipitation, certainly expect most of the area to
remain dry through the end of the long term. However, did note
that most deterministic solutions depict a mid level impulse off
of northern California this weekend and early next week, which
maintains at least a thought for a few thunderstorms in the
vicinity of the Lane County Cascades into the long term. Model
probabilities are too low to warrant inclusion of thunderstorms
in the forecast for now, but will need to monitor this potential
as models start to better resolve this feature in the coming
days. /CB

&&

.AVIATION...Weakening high pressure over the region will
give way to a dying front sliding into northwest Oregon and
southwest Washington Wednesday morning. Marine clouds have been
firmly entrenched along the coast this afternoon and are gradually
pushing into the Coast Range gaps as a strong southwest to west
marine push is underway with the KOTH-KPDX gradient sitting between
6-7mb. This suggests marine clouds should deepen substantially
overnight and push into the Willamette Valley despite most high
resolution model guidance suggesting otherwise. At the moment, high
resolution ensemble guidance suggests a 50% chance that marine
clouds reach KEUG and stay primarily downriver of KPDX & KTTD along
the lowest stretches of the Columbia River. Given the solid sea
breeze currently observed at KEUG, KCVO, KS12 and KMMV, and the
aforementioned observed pressure gradients, have hedged towards MVFR
ceilings being more likely than not with the latest TAF package for
inland taf sites Wednesday morning. The aforementioned dying front
will push onto our northern coastal zones around daybreak on
Wednesday with a 60-70% chance for drizzle and light rain at KAST
between 12-20z Wednesday. The odds the front hangs on enough to
produce measurable drizzle or light rain and impact visibilities for
the Portland metro taf sites is 10-20% and drops to well below 10%
as one goes southward in the Willamette Valley.

PDX AND APPROACHES...Weakening high pressure over the region will
give way to a dying front sliding into northwest Oregon and
southwest Washington Wednesday morning. Marine clouds are gradually
pushing into the Coast Range gaps as a strong southwest to west
marine push is underway with the KOTH-KPDX gradient sitting between
6-7mb. This suggests marine clouds should deepen substantially
overnight and push into the Willamette Valley despite most high
resolution model guidance suggesting otherwise. Given the solid sea
breeze being observed at KEUG, KCVO, KS12 and KMMV currently, and
the aforementioned current pressure gradient, have hedged towards
MVFR ceilings arriving between 12-15z Wednesday for the Portland taf
sites. The aforementioned dying front will push towards the taf
sites between 15-18z Wednesday, but the odds the front is strong
enough to wring out measurable drizzle or light rain and impact
visibilities for the Portland metro taf sites is 10-20%.

&&

.MARINE...A typical summertime pattern persists through much of
the coming week as surface high pressure offshore maintains north
to northwest winds across the coastal waters. North winds will
shift southerly tonight as a weak weather system moves through the
waters before shifting northerly again Wednesday night. Winds are
forecast to remain less than 10 kts through Thursday afternoon.
Next chance of Small Craft Advisory conditions is Thursday night
into the weekend where there is a 50-80% chance of wind gusts over
21 kts, highest probabilities in zones PZZ272, 273, 252, and 253.
Seas will remain in the 4-6 ft range through the weekend,
comprised mainly of short period wind-driven waves and a
modest, mid-period westerly swell. -HEC

&&

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

&&

$$

www.weather.gov/portland

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