146
FXUS66 KPQR 012217
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
317 PM PDT Tue Jul 1 2025

.SYNOPSIS...Hot and dry weather continues today, though cooler
than Monday. Highs will still reach into the upper 80s to around
90 degrees across the interior. Isolated thunderstorms remain
possible across the Lane and Linn County Cascades this afternoon
through tonight. A cooling trend begins tomorrow, bringing more
seasonable conditions through the weekend. There are signs that
warmer temperatures may return early next week as upper level
ridging begins to rebuild.

&&

.DISCUSSION...Tuesday Afternoon through Monday...Radar imagery at
2 PM PDT on Tuesday afternoon shows scattered thunderstorms have
formed just to the south and to the east of Lane County. SPC
mesoanalysis depicts a shortwave along the low pressure system
lingering over California has brought moisture into central Oregon,
with elevated RHs at 925 mb and 850 mb. Guidance continues to
indicate that a 15-25% chance that thunderstorms could form along
the Lane and Linn County Cascade crest this afternoon and evening
due to this increased monsoonal moisture plus lift from the
shortwave. Additionally, latest runs of some CAMs indicate
isolated thunderstorms could continue through the overnight
hours for the same region, so have bumped up the thunderstorm
chances in the forecast to 15% to account for this. Main
concerns with thunderstorms are lightning, gusty winds, and
small hail.

High pressure remains over the region, though is beginning to shift
east. High temperatures will be warm though not quite as warm as
yesterday. Observations at 2 PM PDT are in the mid to upper 80s
across the Willamette Valley, which is on track to peak in the upper
80s to low 90s. Additionally, tightened pressure gradients are
producing another round of breezy north to northwest winds across
the coast, lower Columbia River, and Willamette Valley this
afternoon and evening. Expect gusts up to 25-30 mph along the coast
and 20-25 mph elsewhere into this evening.

By tonight and into Wednesday, the upper ridge continues to weaken
and shift east as troughing takes hold across the Pacific Northwest.
This will bring cooler, more stable conditions with a return to weak
onshore flow. Expect inland highs in the low 80s and coastal areas
holding in the 60s to low 70s.

This cooler pattern appears likely to persist into the holiday
weekend, with ensemble guidance in strong agreement on broad
troughing through at least Saturday. Highs in the Willamette Valley
are expected to range from the upper 70s to low 80s, which is near
to slightly above early July climatological norms. Persistent
onshore flow may also promote morning marine stratus, especially in
low lying interior areas.

By Monday of next week, ensemble guidance begins to suggest a
transition toward zonal flow, with indications of upper level
ridging re-establishing over the western US. However, ensemble
clusters begin to diverge significantly beyond Sunday, introducing
forecast uncertainty for the early part of next week. Inland
temperatures may begin to rebound, potentially returning to the
upper 80s, though confidence in the magnitude and timing of this
warming is still limited. Surface winds are expected to remain north
to northwesterly both along the coast and inland, which may help
maintain marine influence in some areas. -HEC/Hall


&&

.AVIATION...Latest satellite imagery shows a continued narrow
strip of marine stratus resulting in IFR/LIFR cigs at KONP. KAST
has cleared out as of 22z Tuesday, however the marine stratus deck
is only a few miles to the west of the terminal and will most
likely fill back in towards 00z Wednesday. Inland, VFR conditions
will continue under mostly clear skies. Isolated thunderstorms
along and east of the Cascade crest this afternoon and evening may
result in high clouds associated with convective debris, however
cigs would remain VFR for inland terminals. Diurnal winds out of
the N to NW will increase to 15-20 kt gusting to 25 kt along the
coast, and to 10-15 kt with gusts reaching 20 kt along the Lower
Columbia including KPDX this afternoon. Winds will ease tonight.

PDX AND APPROACHES...VFR conditions will continue through 18z
Wednesday under mostly clear skies. NW winds around 10-15 kt with
gusts up to 20-25 kt will continue through 04z Wednesday before
subsiding to 8-10 kt after 06z Wed. -TK/Picard

&&

.MARINE...Persistent surface high pressure offshore will result in
continued north to northwesterly winds across the waters through
the week. Breeziest conditions are expected today, with gusts up
to 25 kt through this evening most likely south of Cape
Foulweather, easing to 15-18 kt or less by tomorrow. Small Craft
Advisories remain in effect through 5 PM this afternoon north of
Cape Falcon, and through 11 PM this evening from Cape Falcon south
to Florence. Choppy seas of 7-9 ft at 7-8 seconds will continue
through today, before subsiding to 3-6 ft tomorrow through the
weekend as winds weaken. -TK/Picard

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 5 PM PDT this afternoon for PZZ251-
     271.
     Small Craft Advisory until 11 PM PDT this evening for PZZ252-
     253-272-273.
&&

$$

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