168
FXUS66 KPQR 062134
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
234 PM PDT Tue May 6 2025

.SYNOPSIS...Warm and sunny this afternoon as high pressure
remains overhead. A weak system will bring cooler and cloudier
weather for Wednesday, possibly accompanied by very light rain
Wednesday afternoon and evening. Benign conditions persist into
the weekend as temperatures rebound into the upper 70s for
Friday and Saturday. Cooler and potentially wetter weather looks
to return Sunday into next week.

&&

.SHORT TERM...Now through Thursday Night...Mostly sunny skies
prevail across the are this afternoon as a narrow ridge of high
pressure remains over the region, allowing temperatures to climb
into the low 80s in many locations in the interior valleys. Weak
offshore flow has allowed coastal areas to warm into the low 70s
in some locations. Visible satellite shows a few high cirrus
clouds starting to move into the area ahead of the next system
as the ridge axis begins to shift east of the Cascades.

This system will arrive on Wednesday as a shortwave trough moves
across the Washington Coast and into southern British Columbia
by Wednesday evening, dragging a weak surface cold front across
western Oregon during the afternoon. Expect high temperatures
on Wednesday to run 10-15 degrees cooler than today as a result,
with highs in the interior valleys closer to 70 and coastal
areas back down in the upper 50s. The front will bring drizzly
conditions to the coast and a chance for some light rain inland,
but rainfall amounts continue to look minimal. The latest NBM
guidance is advertising a 40% chance for any measurable
rainfall in the Portland area through Wednesday night and
closer to a 20% chance farther south towards Eugene, but the
probability of getting a tenth of an inch is 10% or less for the
Willamette Valley and only 15-20% even along the coast.

Expect benign onshore flow on Thursday as any precipitation
departs the area in the wake of the trough, yielding pleasant,
seasonable conditions with high temperatures again around 70
degrees. /CB


.LONG TERM...Friday through Tuesday...Friday and Saturday will
bring another warming trend as 500 mb heights rise on the
periphery of a stout upper level ridge building over the
western CONUS. Currently expect highs in the mid to upper 70s
for the interior valleys both days, with NBM giving the Portland
area around a 50% chance to reach 80 degrees on Friday and a
40% chance on Saturday. Coastal areas are likely to remain
cooler during this period as low level onshore flow persists
over the area. There is increasing confidence in a return to
cooler and wetter weather from Sunday into the early part of
next week, the details of which remain in flux as all WPC
ensemble clusters depict some version of upper level troughing
over the region but with notable differences in position and
magnitude. The long term forecast thus reflects a middle ground
NBM-heavy approach with temperatures slightly below seasonal
normals and broad brushed chances of precipitation. /CB

&&

.AVIATION...VFR conditions and clear skies will persist through
the TAF period for inland terminals. Could see winds slightly
elevated to around 8-10 kt during the afternoon, before 02Z
Wednesday. Through the afternoon, winds will keep easterly for
terminals along the Columbia River, and northerly for the rest of
the inland terminals. With high pressure, temperatures will rise
considerably under the ridge which will increase chances for
thermals along runways, and potentially some minor air density
challenges. While not extremely warm, it is hotter than normal for
the area.

For coastal terminals, expect VFR conditions to persist this
afternoon and then deteriorate to IFR/LIFR conditions around
07-09Z Wednesday as a weak front moves in. Guidance suggests a
40-60% chance of IFR/LIFR conditions after 07Z Wednesday, then
improving conditions possible around 16-18Z Wednesday. Expect
north to northwesterly winds around 8-10 kt with gusts up to 18 kt
possible until 02-03Z Wednesday, then becoming light through at
least 18Z Wednesday.

PDX AND APPROACHES...VFR through the TAF period. Warm
temperatures, with thermals possible through this afternoon.
Easterly winds up to 8 kt will become light and northwesterly
by 06-08Z Wednesday. ~Hall


&&

.MARINE...High pressure will keep conditions settled. Winds are
decreasing but staying northerly. Expect northerly to
northwesterly winds around 10 kt with gusts up to 18 kt over the
next several days. Seas will be 5 to 7 ft at 12 seconds.

On Wednesday, a weak front will push over the waters. It will not
be overly impactful but could see slightly more gusty conditions,
especially in PZZ273, where gusts could reach 20 kt at times.

High pressure returns through the remainder of the week with
little change in conditions.
~Hall

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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