521
FXUS66 KPDT 110504
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1004 PM PDT Wed Jun 10 2026

.KEY MESSAGES...
- Drying and warming trend through early next week

- Locally breezy northerly winds developing over the weekend

&&

.DISCUSSION...
Today: Satellite imagery this afternoon shows an
upper shortwave trough has exit the region, with mainly cloudy
to partly cloudy conditions across the eastern half of the
forecast area. Behind the shortwave exit, winds have started to
weaken and radar shows showers are diminishing across the
eastern mountains. This will be the trend through the remainder
of today, with dry conditions and light winds returning late
this evening.

Thursday through Sunday: The region will sit between an
amplifying upper level ridge offshore and a broad trough centered
over the northern Great Plains through the weekend. Conditions
will remain dry across the forecast area through this period,
while diurnally driven winds develop Thursday and Friday. Over
the weekend, ensemble guidance is in good agreement of shortwave
troughing diving down the northern Rockies, which will clip the
PacNW. This will shift surface winds to the north and northeast
Saturday and Sunday, with locally breezy winds (10-20 mph)
developing from the Columbia Basin into central OR in the
afternoons. This will lead to elevated fire weather conditions
across portions of the OR Columbia Basin Saturday and Sunday
afternoons, though chances of Red Flag thresholds being met are
only 25-40% Saturday and 35-50% Sunday.

Sunday, ensemble cluster guidance is in good agreement that the
upper level ridge offshore will move closer to the PacNW, which
will introduce chances (30-50%) of hitting 90 degrees across
portions of the Columbia Basin and eastern Gorge.

Monday and Tuesday: Most recent ensemble cluster guidance is in
good agreement that the upper level ridge will slide inland
Monday, limiting wind concerns but also increasing the warming
trend across the lower elevations, with mod-high confidence
(65-80%) of widespread low to mid 90 degree high temperatures
developing Monday afternoon. With the ridge axis moving
overhead, winds will become light, which will limit fire weather
concerns to the very dry conditions in the lower elevations.

By Tuesday, great agreement remains in the upper ridge breaking
down as it moves further inland, bringing the peak of the
warming trend in the afternoon as well as introducing breezy to
locally windy conditions to the intermountain PacNW (confidence
60-70%). Looking to the NBM, there is a 30-50% chance of 100
degree temps developing Tuesday afternoon along the I-82
corridor from Hermiston to Yakima, as well as in the Walla
Walla valley and eastern Gorge. Currently, probabilistic
HeatRisk guidance shows a 10-40% chance of Major HeatRisk
developing across the Columbia Basin and eastern Gorge Tuesday.
If this trend continues, heat products may need to be issued for
some portions of the Columbia Basin early next week. Lawhorn/82

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...

Clear sky and dry boundary layer will leave VFR conditions for
all terminals. As the high pressure becomes the dominant
weather driver, winds remain below 8 knots for the duration of
the TAF.


&&

.Preliminary Point Temps/PoPs...
PDT  41  79  49  80 /   0   0   0   0
ALW  47  79  53  81 /   0   0   0   0
PSC  44  83  51  85 /   0   0   0   0
YKM  44  82  51  85 /   0   0   0   0
HRI  43  82  52  84 /   0   0   0   0
ELN  40  77  48  78 /   0   0   0   0
RDM  34  80  44  83 /   0   0   0   0
LGD  38  78  44  78 /   0   0   0   0
GCD  36  81  43  82 /   0   0   0   0
DLS  47  82  55  84 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...None.
OR...None.

&&

$$

DISCUSSION...82
AVIATION...71