388
FXUS66 KPDT 110537
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1037 PM PDT Thu Sep 10 2026

.KEY MESSAGES...
- Breezy winds and dry conditions Today - Elevated Fire Weather

- Isolated thunderstorms Saturday

- Widespread showers Saturday through Sunday morning

&&

.DISCUSSION...
Zonal flow was developing with an increasing mid level heights
gradients Today. HiRES models show a weak trough
forecast/placed across the Interior and Pacific NW by about 7 am
Friday. This is the initial mass adjustment in advance of a
more robust upper low poised to move onto the PAC NW coast on
Saturday. Both of these features will have weather implications,
with a chance for thunderstorms being the highest risk element
on Saturday.

Winds Today will increase though the late afternoon across the
eastern Columbia River Gorge, the Columbia Basin of Oregon/Blue
Mt foothills as well as though the Kittitas Valley, with speeds
from the HRRR showing about 15 up to locally 20 knots./ Gust
potential in these areas is in the 20 to 25 knot range and
locally higher around Dallesport. LAV guidance maintains breezy
winds through the evening hours as the upper wave moves into the
region spreading light showers across the area. The best
forcing for these showers as typical is across the Blue Mts
where trace to a few hundredths of an inch of rain is forecast
by the HREF. Most of the area will just see clouds whereas a
Trace to a few hundredths of an inch area possible around
midnight along the Blue Mts of Oregon.

The aforementioned system will leave Friday cooler (post cold
front), in the 60s and 70s. Breezy conditions very early Friday
morning will gradually ramp down to light (under 10 knot)
through the morning.

Saturday look quite low risk for convection given the sub 50
J/kg SBCapes developing and probability of thunder under 10% now
by the NBM mean. The 75th percentile NBM only averages 50 to
150 J/kg CAPE across the higher terrain with no improved ts
chances, which really do not start to register until the early
evening and overnight hours. With the later start now being
shown, the Cascades and the Blue Mts of Oregon are showing about
a 15-20% chance of a wetting rain (0.10) by 5 pm, while much
greater probability (50-70%) exists though midnight over the
Cascade eastern slopes, the central Oregon Mts through the Blue
Mts of Oregon. Sunday remains wet based on these trends. With a
48 hour expected precipitation around a quarter of an inch over
central Oregon to three quarters of an inch to one inch across
the highest mountain zones. Considering uncertainty in outcomes,
the ranges in this highest amounts could be from around a
quarter inch on the low end (25th percentile) to an inch and a
half (at the 75th percentile).

The balance of the week looks dry with a gradual warming trend
peaking Thursday with still seasonable 70s and low 80s across
the region.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
VFR conditions prevail at all TAF sites through the period. On
going light showers over PDT and the Blue Mountains and are
forecasted to end at 12Z. Winds are slated to move to calmer
conditions as the day progresses with the largest changes
occurring in wind direction rather than speed.

&&

.Preliminary Point Temps/PoPs...
PDT  48  72  46  72 /  30   0   0  10
ALW  53  74  52  74 /  30   0   0   0
PSC  53  77  49  77 /  10   0   0   0
YKM  51  74  52  73 /   0   0   0  20
HRI  53  76  47  76 /  10   0   0   0
ELN  47  70  48  69 /   0   0   0  10
RDM  46  74  39  66 /   0   0   0  40
LGD  49  73  46  76 /  40   0   0  30
GCD  49  75  46  77 /   0   0   0  30
DLS  52  76  53  74 /   0   0   0  20

&&

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

&&

$$

DISCUSSION...71
AVIATION...18