366
FXUS65 KBOI 290605
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1205 AM MDT Sat Aug 29 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Scattered showers and isolated thunderstorms through Saturday.
  Stronger storms possible in SW Idaho on Saturday.

- Cool and dry Sunday then warmer early next week.

- A deeper low pressure system expected later next week for
  cooler and wetter conditions.

&&

.SHORT TERM /Through Monday Night/...
Issued 227 PM MDT FRI AUG 28 2026
Showers will and isolated thunderstorms will continue across
southwest Idaho and far SE Oregon into Saturday. A couple of
highlights include shortwave energy lifting out of the Great
Basin this evening and a cold frontal passage Saturday evening.
The shortwave trough this evening will act to increase the
potential for thunderstorms from the OR/ID/NV border area
northeastward into the Boise mtns through late evening. Gusty
winds to 40 mph would be the main threat from heavier showers
and thunderstorms through Midnight. Shower and thunderstorm
potential will continue across SW Idaho on Saturday, while
dropping off across SE Oregon. Passage of a cold front Saturday
evening will usher in a cooler air mass on gusty northwest
winds. Precipitation will taper off behind the front Saturday
night leaving dry conditions across the region on Sunday.
Temperatures Sunday will run about 10 degrees below normal,
putting lower elevations in the upper 70s. Sunday night will be
dry with many sites dropping into the upper 40s or colder.

&&

.LONG TERM /Tuesday through Saturday/...
Issued 227 PM MDT FRI AUG 28 2026
Conditions slowly cool and become more active through the long
term as a broad trough along the coast amplifies and a strong
closed low pressure system moves along the trough axis. As the
trough axis develops Monday and Tuesday, most of the area moves
into the deformation zone between a shortwave ridge and
shortwave trough. This means rebounding up to seasonal averages
on Monday inside the ridge, and increased shower and
thunderstorm chances in south central Idaho. The shortwave ridge
moves out Tuesday as another shortwave trough moves through,
this time further north and west, covering much of the forecast
area. Temps are mostly unchanged Monday into Tuesday, but
enhanced storm potential moves from south central Idaho over
higher terrain in central and southwestern Idaho as well as
eastern Oregon.

Temperatures cool properly to 10 degrees below normal Wednesday
through Friday as the strong closed low moves along the trough
axis and stalls over the Oregon coast. Unsettled and gusty
conditions are expected in the broader region, although the
exact placement of storms/showers is still uncertain. The strong
pressure gradient aloft is likely to mix down to the surface
ahead of the low, leading to widespread gusts each afternoon
Tuesday through the extended period.

&&

.AVIATION /06Z Saturday through Sunday/...
Issued 1205 AM MDT SAT AUG 29 2026
Isolated to scattered light rain showers and virga across S Idaho
and far SE Oregon will continue overnight into Saturday. Isolated
thunderstorms will also develop with gusty erratic winds 25-45 kt
possible on Saturday. Local reductions in visibility from wildfire
smoke. Surface winds: SE-W 5-15 kt, becoming NW Saturday evening
along a cold front. Localized gusts 15-25 kt overnight, with gusts
20-30 kt Saturday afternoon/evening. Winds aloft at 10kft MSL: SW 15-
25 kt.

KBOI...Overcast mid to high clouds. Occasional light showers/virga
in the vicinity through Saturday, with a 10% chance of a
thunderstorm late afternoon/evening. Surface winds SE 5-15 kt with
gusts up to 25 kt overnight, becoming light and variable to NW by
Saturday morning.

Sunday Outlook...Decreasing clouds and dry. Surface winds W-NW 5-15
kt, afternoon gusts 20-25 kt in S-central Idaho.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.

OR...None.

&&

$$

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AVIATION.....ST
SHORT TERM...DG
LONG TERM....JM