642
FXUS66 KPQR 252039
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
138 PM PDT Tue Jun 25 2024

.SYNOPSIS...Low pressure will arrive later tonight and Wednesday,
bring cooler temperatures, clouds and even a few showers. Best chance
of showers will be Wednesday night. Dry and mild for Friday into
Saturday. But, another low pressure arrives, bringing another bout of
cooler temperatures and better chance of showers for Sunday into
early next week.
&&

.SHORT TERM...Tuesday night through Friday...
One more rather summery feeling evening, under mostly clear skies.
Low pressure offshore will be approaching overnight, and will allow
for increasing onshore flow and cooler marine air to filter from the
coast to the interior overnight.

That offshore low pressure will bring much cooler conditions to the
region on Wednesday. Will also see much more in way of clouds late
tonight into Wednesday. Overall, temperatures will stay in the 60s
along the coast, and lower to mid 70s across the interior. Will
maintain some chance of showers along the coast and across the
southwest Washington zones for Wed, but not all that convinced will
get much over the Oregon part. Bulk of the upper support for showers
seems to be farther to our north. So, will trend forecasts as such,
with generally dry weather for areas to the south of a Newport to
Portland line, and fairly decent chances (over 70%) for areas of the
higher terrain of southwest Washington, including the Willapa Hills
and the Cascades. Better chance of showers is Wed night, as another
upper disturbance in the flow shifts inland. With this one a bit more
south, more reasonable to support higher chances for showers over
much of the region. Still, rainfall (for those lucky) will be quite
variable, with 0.15 up to 0.33 inch generally for southwest
Washington and far northwest Oregon, down to a trace to 0.10 inch
across Lane County.

Showers lingering into Thursday. After morning clouds, will see
clouds gradually break up through he afternoon. Mild day, with highs
in the 60s along the coast, and lower to middle 70s inland.

High pressure rebounds over the region for Thu night and Friday. As
such, Friday will be a somewhat warm day for the interior, with highs
in the upper 70s to lower 80s for the interior, and mid to upper 60s
along the coast. All and all, not bad for late June.

.LONG TERM...Saturday through Tuesday...Weak ridging into early
Saturday will give way to another trough. This next system will bring
a better chance of showers, mainly later Sat night through Sun
evening. Temperatures stay on cooler side, thanks to clouds. Overall,
looks like upper 60s to mid 70s at most for highs, with warmest well
inland. Still unsettled into early next week, as upper trough still
hanging over the Pac NW. Will maintain chance of showers for Monday,
and could be even for Tuesday. Models still in flux a bit for
Tuesday, as could be dry as well. But, temperatures slowly moderating
back to seasonal levels by Tuesday, with upper 60s on the coast and
mid to upper 70s inland.     /Rockey

&&

.AVIATION...High pressure remains over the region today, with dry
southwest flow aloft. VFR expected through this evening. Tonight,
an upper trough approaching will increase southwest flow inducing
stronger onshore flow at the low levels. This will likely bring
stratus to the coast later tonight through Wednesday morning.
Probabilities of CIGs MVFR to IFR increase to 70-90% after 06Z
Wed near KONP and 09Z Wed near KAST. Chances for rain showers also
increases along the coast by Wed morning. Guidance also suggests
that marine stratus begins to push into the southern Willamette
Valley after 12Z Wed with a 60-80% chance of MVFR near KEUG
through 18Z Wed. Winds generally northerly less than 10 kt today,
but 10 to 15 kt at the coast this afternoon. Winds back to
southwest tonight.

PDX AND APPROACHES...VFR under mostly clear skies through tonight.
Approaching front will bring increasing mid to high level clouds
on Wednesday. Northwest winds 4-6 kt shift southwesterly by 12Z
Wed. /DH
&&

.MARINE...High pressure weakens as a weak front approaches the
waters. North to northwesterly winds around 10-15 kt ease
overnight followed by a southerly wind reversal Wednesday morning.
Winds are expected to remain below 20 kt. High pressure builds
across the waters again for Thursday and Friday, bringing a return
of northerlies. Seas remain in the to 4 to 6 ft range through
most of the week as a westerly swell moves across the waters.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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