384
FXUS66 KPQR 060828
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
128 AM PDT Sun Jul 6 2025

.SYNOPSIS...High pressure with onshore flow at the surface and
northerly flow aloft. Warming temperatures through Tuesday with
Moderate HeatRisk in the inland lowlands. Cooler on Wednesday
and Thursday as a low aloft moves in, and then warming late in
the week with another ridge of high pressure.

&&

.SHORT TERM...Now through Tuesday night...Broad area of high
pressure builds through early next week. At the same time, an
upper level low will park over northern California through
Tuesday. This low will enhance northerly to northeasterly flow
aloft while maintaining onshore flow at the surface. Clear skies
with this type of flow pattern will lend itself to warming
temperatures and dry weather. Through Tuesday, prepare for
temperatures to rise a few degrees each day. Overall, models are
in good agreement in the pattern with only around a 5 degree
spread between the 90th and 10th percentile. Monday and Tuesday
will be the warmest with highs in the 90s inland, including the
Cascade Valleys, and in the upper 60s along the coast. In the
warmest solution, inland valleys could see temperatures as warm
as 94 degrees F, though there is only a 10% chance of that
occurring. Through the central and southern Willamette Valley
and along the coast, winds will turn more northerly in the
afternoons on Sunday through Tuesday. This direction means that
we could see some gustier conditions with peak gusts as high as
25 mph.

On both Monday and Tuesday Moderate HeatRisk is present within
the Willamette Valley, Clark County lowlands and the Gorge.
Those sensitive to heat should take precautions. -Muessle

.LONG TERM...Wednesday through Saturday...The high pressure
ridge will degrade late Tuesday into Wednesday as the low aloft
shifts inland. It will move into eastern Oregon and southern
Idaho by Wednesday afternoon. As it makes this shift conditions
will cool as onshore flow becomes stronger. 850 mb temperatures
will drop from 16 deg C on Tuesday to 9 deg C on Wednesday. One
newer feature that hasn`t been realized yet in previous model
runs is a weak meso-low and shortwave trough at the mid-levels
forming over Washington. The added instability combined with
moister air and cooling temperatures is bringing a slight chance
(less than 25%) of very light precipitation to southwest
Washington, and less than a 10% chance of isolated showers
along the Central Oregon Cascades. Confidence is very low though
as the pattern could easily shift if the low tracks a bit
further north. In this case, we would be rain free. With all
that said, any precipitation that does fall will be light,
minimal (if any) accumulation, and will be short lived.

Thursday will be dry once again with near normal high
temperatures in the 80s inland. In the evening, a forming low
aloft will pass over the northern Rockies, and yet another mid-
level low moves over northern California in almost the same
pattern as Monday/Tuesday. Could see a rapid warm up on Friday,
especially for central and southern Willamette Valley locations.
The pattern overall is less realized than the one earlier in
the week and therefore confidence is low at this time. A big
factor to consider is that the NBM is currently running closer
to the 90th percentile of the ensemble clusters. Therefore, it
is potentially skewed a little too warm. While we cannot rule
out these high of temperatures, it is important to note that
the long term forecast will change. -Muessle


&&

.AVIATION...VFR conditions continue across the region beneath
largely clear skies aside from passing high cirrus. Stratus
extending south from the WA coast will likely reach NW OR coastal
terminals by 15z Sun, however coverage looks to remain low enough
to merit only a 20-25% chance of MVFR cigs at AST, and even lower
chances to the south at TMK/ONP. Marine stratus will redevelop
this evening after 03-06z Mon, bringing mixed MVFR/IFR cigs.
Inland terminals may also see few-sct low stratus along the
Cascade foothills early, with less than a 5% chance of MVFR cigs.
Any stratus will mix out by 16-18z Sun, leaving mostly clear skies
through the remainder of the period. Diurnal north to northwest
winds continue, albeit stronger than recent days, rising to 10-20
kt with gusts of 20-30 kt after 18-21z Sun, then easing to 10 kt
or less by 06-09z Mon.

PDX AND APPROACHES...VFR conditions beneath largely clear skies
expected throughout the period. Few low stratus may develop along
the Cascade foothills by 15z Sun, but chances for MVFR cigs have
trended lower to less than 5% in the Portland area. Diurnal
northwest winds rise to 10-15 kt with gusts of 20-25 kt after 21z
Sun, before easing below 10 kt by 06-09z Mon. -Picard

&&

.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. A few gusts to
20-25 kt cannot be ruled out across the nearshore waters south of
Cape Falcon through tonight, but sufficient coverage to warrant
an advisory is not anticipated. Inland heating will drive a
strengthening coastal pressure gradient, resulting in increasing
winds today and Monday. Small Craft Advisories remain in effect
across the waters midday today through Monday evening as winds
gust to 25-30 kt. Expect the strongest gusts south of Cape Falcon,
while conditions will be more marginal to the north across the
mouth of the Columbia and the south Washington coastal waters.
Seas will remain 4-6 ft, comprised mainly of short period wind-
driven waves and a modest, mid-period westerly swell. -CB/Picard

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory from 11 AM this morning to 10 PM PDT
     Monday for PZZ251>253-271>273.
&&

$$

www.weather.gov/portland

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