584
FXUS66 KPQR 071025
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
325 AM PDT Mon Jul 7 2025

.SYNOPSIS...High pressure lingers through Tuesday with a low
spinning over northern California aloft. Temperatures will be in
the upper 80s to low 90s through Tuesday but will quickly cool
on Wednesday as the low moves inland. Slight chance for showers
on Wednesday in southwest Washington. Warmer temperatures return
late in the week though confidence is quite low.

&&

.SHORT TERM...Now through Wednesday Night...High pressure
continues to build over the northeast Pacific which will keep
conditions dry and cause temperatures to rise. Sunday highs
ranged from the mid 80s within the Willamette Valley to 60-70
degrees F along the coast, and near 80 deg F within the Cascades
and foothills. Keep these temperatures in mind as we dive into
today`s forecast. This morning, low temperatures are around 5 degrees
warmer than Sunday morning which means that we are already
starting with a leg up for even warmer temperatures today.
While higher resolution models are trending a little cooler than
the NBM mean, these warmer temperatures overnight further support
the warmer daytime temperatures of the NBM. Still will see
Moderate HeatRisk for the inland valleys including the Gorge and
valleys within the Cascade Foothills. With the thermal trough
forming to the south, expecting northerly winds along the coast
and the Willamette Valley. Gusts up to 20 mph are possible. Will
note that humidity will be low (around 25-30% RH) within the
Willamette Valley and along the Cascades.

Minimal difference in the forecast for Tuesday in regards to
temperature and impacts. In the evening, the ridge will begin
to break down though as a low aloft that is sitting near
northern California begins it`s inland trek. Winds aloft will
shift to the northwest and usher in a moister airmass. Winds
will become gusty along the Coast Range ridgetops, the gaps into
the Willamette Valley and Gorge near Hood River. There is
around a 30% chance of gusts greater than 30 mph in the Upper
Hood River Valley and exposed terrain in the Gorge. Will note
that as the low shifts inland, there are a few shortwaves
forming in the mid-level flow. Some wrap around moisture is
possible with the initial passage of the low, but confidence is
very low on whether or not precipitation is possible along the
Cascades. The NBM is showing around a 10% chance of very light
showers over the Cascades Tuesday night. However, given the
pattern, showers should remain east of the Cascades.


Wednesday will see an increase in the onshore flow as a
shortwave trough digging down over Washington from the north,
and the low that sat over northern California advects eastward.
This trough brings around a 20-40% chance of light showers to
southwest Washington with most of northwest Oregon evading the
rain. Temperatures will swing around 10 deg F cooler inland as
the onshore flow increases. -Muessle


.LONG TERM...Thursday through Sunday...Uncertainty increases
considerably in the long term forecast. Global ensembles are in
good agreement in a broad area of high pressure forms over the
Pacific on Friday with a thermal trough at the surface. In this
scenario, north-easterly winds will dominate aloft with 850 mb
temperatures around 18 deg C. These warm temperatures will mix
down to the surface bringing surface highs to similar values to
what is expected Monday. With the dry air moving in, will see
dropping daytime humidity and gusty winds from the north.

On Saturday some of the global models are suggesting another
shortwave trough forming over the Oregon/California border. This
trough could shake up the forecast a bit if it were to
manifest. For example, looking at the ensemble clusters, one
ensemble cluster is showing a decrease in heights from the mean
and thus, suggesting temperatures will be lower. Onshore flow
is forecast to increase on Saturday and Sunday though so
humidity should be higher, especially in the northern portions
of the forecast area. Others pattern options  though are
continuing a warm pattern. The pattern over the weekend is
chaotic so confidence is incredibly low. -Muessle


&&

.AVIATION...VFR conditions at all inland terminals throughout the
period, with a 40-70% chance of IFR ceilings or lower at coastal
terminals through 18z Mon due to marine stratus. LIFR fog may be a
possibility as well at coastal terminals, though this is only
expected at the immediate coast. After 18z Mon, coastal terminals
trending towards VFR for the rest of daytime hours (90%
confidence). Winds presently are fairly weak, under 5 kts at all
terminals as of 10z Mon. However, daytime hours will bring diurnal
heating back, and northerly gusts up to 25 kts at the coast and 20
kts inland are expected from 16-18z Mon onwards, continuing until
5-7z Tue.

PDX AND APPROACHES...Clear sky VFR conditions throughout the
period. Winds remain under 5 kts for the rest of Sunday night, but
increase to see northerly gusts up to 20 kt between 18z Mon to 5z
Tue. -JLiu

&&

.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. Relatively strong
pressure gradient at the coast due to diurnal heating, and
elevated winds remain in place for all coastal waters through
Monday night. Small Craft Advisories remain in effect through
Monday evening as wind gusts increase a bit more to 25 to 30 kt
Monday. Expect the strongest gusts south of Cape Falcon, while
conditions will be more marginal to the north across the mouth of
the Columbia River and the south Washington coastal waters. Seas
will remain in the 4-6 ft range, comprised mainly of short period
wind- driven waves and a modest, mid-period westerly swell.
-CB/JLiu

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 10 PM PDT this evening for
     PZZ251>253-271>273.
&&

$$

www.weather.gov/portland

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