051
FXUS66 KPQR 061747
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1047 AM PDT Sat Jun 6 2026

Updated aviation discussion.

&&

.SYNOPSIS...A series of frontal systems continue progress
through Pacific Northwest into next week facilitating cooler
than normal temperatures and periodic rounds of showers through
Wednesday, June 10. There is also a 15-35% chance of short-
lived thunderstorms this afternoon and a 10-20% chance Tuesday
afternoon. Upper level ridging will bring a warming and drying
trend Thursday onward (June 11-15), with a growing potential for
heat related concerns June 12-15.

&&

.SHORT TERM...Now through Monday Night...Currently satellite
and radar observations early this morning show our next weather
system in the form of an upper-level trough beginning to
increase showers across the region, a trend anticipated to
continue as the day progresses. The latest Convective Allowing
Model (CAM) guidance highlights an increase during the midday
and afternoon hours, likely the result of a daytime heating,
cooling temperatures aloft, and added synoptic scale lift as the
axis of the upper level trough comes onshore. These conditions
support a 15-30% chance of thunderstorms over northwest OR and
southwest WA into early evening hours (mainly north of a line
extending from Florence to Eugene to Oakridge). Based on
deterministic model soundings, MUCAPE values of 200-400J/kg
should extend into the -10 to -20C mixed-phased region of the
atmosphere facilitating charge separation and thus lightning
production within the strongest cells. As such, the strongest
cells this afternoon will have the potential to produce brief
heavy rain, small hail, gusty outflow winds, and a few flashes
of lightning. It is worth noting that any given stronger
convection will be short-lived and sub-severe as wind shear is
limited and organized convection is not expected. There will
also be breaks in precipitation in between showers, so those
spending time on outdoor activities should not expect an all-day
washout. Nevertheless, have your rain jackets handy as it is
unlikely any given location will stay dry the entire day. As
always, when thunder roars go indoors.

Come Saturday evening into early Sunday morning, deterministic
and ensemble models remain in good agreement depicting the
upper level trough axis quickly shifting east of the Cascades,
allowing for a weak transitory ridge of high pressure to pass
overhead. This leads to a period of dry weather for much of
Sunday. However, our next pacific frontal system arrives late
in the day and/or overnight increasing chances for steady light
stratiform rainfall. There is still noteworthy model
uncertainty regarding the exact arrival of the rainfall with
this feature. A subset of guidance shows rain beginning as early
as 4-9 PM Sunday while other guidance pushes the beginning of
rainfall back as late as 7-10 AM Monday. All members from the
ENS/GEFS/GEPS do eventually show rain arriving with this next
system, despite the timing differences. Once the rain begins,
expect a transition to more showery precipitation for Monday
afternoon. -99/23

.LONG TERM...Tuesday through Friday...The long term forecast
starts out with cooler than average temperatures and occasional
showers followed by growing confidence in a substantial warming
and drying trend late in the week. Despite the model timing
differences discussed above with the arrival of a frontal system
late Sunday into Monday, ensemble guidance is in good agreement
the area will be solidly within a post-frontal shower
environment Tuesday through Wednesday under a broad upper level
trough parked overhead. Expect the continuation of cooler than
normal temperatures and occasional rain with high temperatures
most likely in the 60s. As the axis of the larger trough feature
passes overhead around Tuesday, temperatures aloft bottom out
with the NBM suggesting a 10-20% chance of thunderstorms during
the Tuesday afternoon time period. The latest NBM 48-hr
probabilities for rain amounts over 0.50" peak between 5 PM
Sunday and 5 PM Tuesday, showing anywhere from a 50-75% chance
for most locations in southwest WA and northwest OR, except an
80-90% chance in the Cascades and in the Coast Range/Willapa
hills.

Our focus then shifts to a noticeable warming and drying trend
from Thursday onward. Cluster analysis for June 11-15 for 500 mb
heights generally suggest upper level ridging will gradually
develop over the region. This will bring a prolonged stretch of
dry weather, with temperatures likely warming each day. While
confidence is high temperatures will warm significantly compared
to early in the week, confidence is low regarding exactly how
warm temperatures will get. The NBM ensemble spread reflects
this uncertainty well, for example the NBM 10th-90th percentile
for high temperatures Saturday June 13 through Monday June
15, range from low 80s to near 100 degrees for the inland
valleys and upper 60s to upper 80s for coastal locations. But,
compared to prior NBM runs yesterday this spread has shrunk by
2-5 degrees, albeit in the "warmer" direction. Probabilities
for major HeatRisk begin to hit 10-25% across in the inland
valleys starting Saturday June 13 before increasing to 20-45% by
Monday June 15th. Those who are sensitive to heat and/or have
outdoor plans should definitely keep an eye on the forecast
over the next week. -99/23

&&

.AVIATION...Largely VFR flying conditions expected today with
brief periods of MVFR/IFR restrictions as rain showers and
thunderstorms track eastward across the airspace through this
afternoon. Shower coverage is highest to the north of US-20,
decreasing southward. While a heavy shower may reduce cigs/vis,
the primary aviation concern will be 25-45% chances for thunder
as soon as 19-20z Sat and continuing through 22-24z Sat.
Thunder is less likely south of US-20 (KEUG, KCVO, KONP), and
thus only rain showers are included in the TAFs. To the north,
specific timing within the aforementioned window is difficult to
anticipate, and AMDs will be issued as needed for TSRA/VCTS
when radar and lightning observations depict storms headed for
terminals. Thunder chances will quickly diminish by 22-23z Sat
at the coast and by 00z Sun inland, followed by clearing skies
as rain ends a few hours later. VFR conditions then prevail
through the remainder of the period, although a wet ground
surface followed by clear skies may allow for some low cloud or
fog development in sheltered locales late in the period. West
winds of 8-12 kt at all terminals with occasional gusts of 15-20
kt most likely at the coast will ease below 5 kt after 00-06z
Sun and begin to turn out of the south near sunrise Sunday.

KPDX AND APPROACHES...VFR conditions most likely to prevail
through the period. Scattered rain showers are ongoing as of
1745z Sat, and will continue in a similar fashion through 22-24z
Sat. Chances for thunder remain at 30-40% through that time,
with any storm capable of brief restricted vis/cigs during
heavy rain. Any lingering showers will dissipate by 03-04z Sun.
West winds of 8-10 kt continue through this evening with
thunderstorms generating locally gusty and erratic winds,
becoming light and variable tonight, then rising out of the
south Sunday morning. -36

&&

.MARINE...A fairly progressive weather pattern continues into
next week as a series of frontal systems bring increasing winds
and building seas. Seas this morning currently hold in the 5-8
ft range at ~10 seconds . Another system moves through today
bringing a slight increase in northwesterly winds. However, wind
gusts only have around a 10-35% chance for Small Craft Advisory
wind gusts with the highest probabilities in this range across
the outer waters. Minimal confidence in Small Craft conditions.
After a lull during the day on Sunday as high pressure briefly
returns, winds increase yet again on Monday as a comparatively
stronger system moves over the waters bringing south wind gusts
up to 21-25 kt and seas approaching 5-8 ft. Conditions then
gradually calm into the middle the of the week as a ridge of
high pressure attempts to rebuild overhead and northwesterly
winds return while seas hold around 5-7ft around 9-11 seconds.
Towards the end of next week, those northwesterly winds likely
(60-80%) push above 21 knots across the outer waters south of
Cape Falcon and will be a feature to watch in the long-term. -99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

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