305
FXUS66 KPQR 160110 AAA
AFDPQR

Area Forecast Discussion...UPDATE
National Weather Service Portland OR
610 PM PDT Sat Aug 15 2026

Updated Aviation discussion

.SYNOPSIS...Seasonably warm and dry conditions expected through
the next week with morning clouds and afternoon clearing. Low
chances for Cascade thunderstorms this afternoon, which may
result in lightning with briefly heavy rain and erratic winds.

&&

.DISCUSSION...Now through Friday...Seasonable conditions with no
weather impacts expected through the next week. The large-scale
pattern looks to remain fairly stagnant through the period, with
broad and relatively flat upper-level ridging over the majority
of CONUS and weak positively-tilted upper troughing over the
Northeast Pacific. This pattern will support continued onshore
flow, maintaining near-normal daily high temperatures in the
80s within inland valleys and 60s along the coast, and overnight
lows in the 50s across the region.

A transient shortwave tracking overhead today yielded isolated
light rain showers this morning, however dry conditions are
expected through the remainder of the day west of the Cascades
as the best forcing slides northward into Washington. The robust
marine layer has thus far supported overcast skies, but latest
satellite imagery depicts cloud cover beginning to erode, with
increased sunshine expected through this afternoon. Above the
low-level inversion, there is some available instability to
generate high-base showers or thunderstorms, but those low
chances (15-25%) are restricted to the Cascades where showers or
storms may instead be surface-based. Any passing storms will be
capable of producing lightning as well as briefly heavy rain and
erratic winds. Chances for thunder fall below 5% this evening.

The next chance for light showers or Cascade thunderstorms
appears to be on Monday when the next weak shortwave passes
overhead, however the probability of accumulating rain is less
than 5% away from the immediate Cascade crest. There is
increasing consensus that upper-level ridging over the Rockies
and Great Basin will build late in the workweek, which could
favor warmer temperatures Thursday and Friday afternoons. A
potential passing system Friday into next weekend will bring
higher chances for rainfall, however uncertainty remains high
at this lead time. -36

&&

.AVIATION...Through 00z Monday...Southwest flow aloft continues as
an upper level trough remains offshore. As of 01z Sunday, marine
stratus has eroded across the central and southern Willamette
Valley, though just beginning to scatter out near the Portland
Metro area. Stratus has also retreated off the central OR coast,
but continues to remain entrenched northward from KTMK to KAST
with MVFR CIGs around FL025. High-end MVFR stratus also persists
up the lower Columbia River, including KKLS. Expect clearing to
continue inland this evening with predominately VFR conditions
through at least 10z Sunday. There is around a 20-40% chance that
MVFR stratus returns inland, but confidence is not high enough to
include in the latest TAFs. High confidence that MVFR stratus
persists or returns to the coast tonight, with around a 50% chance
for IFR conditions after 06z Sunday at KONP. West to northwest
winds around 5-10 kt ease below 5 kt tonight.

KPDX AND APPROACHES...High-end MVFR stratus is beginning to
scatter as of 01z, with skies becoming mostly clear after 02z.
Stratus likely builds in again late tonight, with around a 30%
chance for MVFR CIGs between 11-17z Sunday. Northwest winds around
4-6 kt this evening expected to ease overnight. /DH

&&

.MARINE...A largely stagnant pattern continues through much of
the next week with high pressure offshore supporting northerly
to northwesterly winds of 8-15 kt and gusts up to 20 kt. Benign
seas of 3-6 ft persist through the period. -36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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