518
FXUS65 KBOI 292354
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
554 PM MDT Sat Aug 29 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Isolated showers and thunderstorms today. Stronger storms
  producing gusty winds possible in SW Idaho.

- Cool and dry Sunday then warmer early next week.

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

&&

.SHORT TERM /Through Monday Night/...
Issued 201 PM MDT SAT AUG 29 2026
As an upper level low moves across the Pacific Northwest this
afternoon, ahead of an associated cold front will support shower
and thunderstorm development through the evening. Scattered
showers will be capable of wind gusts up to 35 mph and light
rainfall or virga. Embedded in showers, a few thunderstorms are
possible and could produce wind gusts up to 50 mph and moderate
rainfall. The chance of storms is about 10%, mostly north of the
Nevada border and in mountains. While the chance of showers is
20% across much of Southwestern Idaho. At the same time as
showers, southwesterly winds gust up to 25 mph.

The cold front proper moves through later this evening into the
early overnight hours, bringing wind gusts up to 30 mph out of
the northwest through Baker County, the I-84 corridor, and the
Snake Plain. Wind gusts will be strongest in the I-84 corridor
and following the Snake River. The airmass behind the front will
make Sunday about 10 degrees cooler than Saturday and a bit
drier with little to no chance of showers anywhere in the
forecast area. Patchy frost possible Sunday and Monday morning
across the higher valleys of southeast Oregon. Brief shortwave
ridging on Monday will allow temperatures to rebound back toward
normal levels, though shower chances will begin to return to
south central Idaho late Monday night with the approach of the
next upper level low pressure system.

&&

.LONG TERM /Tuesday through Saturday/...
Issued 201 PM MDT SAT AUG 29 2026
Initial closed low off the Pac NW coast will open up and kick inland
late Tue/Wed. This will bring a bump in precipitation chances,
mostly across e-central Oregon and the w-central Idaho mtns. Warm
and breezy conditions will precede this feature on Tuesday with
temperatures 5-10 degrees above normal and gusts across open terrain
approaching 30 mph.

Remainder of the forecast period will be dominated by a deep closed
low that takes position along the OR/WA coast. There is consensus
between deterministic solutions and ensemble mean to keep the closed
low center to our west through Saturday. This puts our region under
southwest flow as the low slowly fills. Looking at the details there
are distinct forecast differences in size of the low and position it
takes. Would put higher confidence on cooler/wetter conditions
across SE Oregon zones for Thu-Sat. The ensemble mean paints 25-50%
chance of precipitation during this period with a focus on Wed/Thur
for the higher probabilities. For southwest Idaho zones, have higher
confidence in cooler temps than seeing wetter conditions due to
likelihood of a dry slot setting up between precipitation circling
the low center and monsoon moisture further to our east. The w-
central mtns would be most favored for precipitation Wed/Thur.
Breezy/gusty winds can be expected through the period, especially
during the afternoon/evening. Typically favorable spots for the
strongest winds in this pattern are SE Oregon and higher terrain
south of the Snake Plain. Starting Thursday temperatures will run
about 10 degrees below normal (mid-upper 70s in Snake Plain).

&&

.AVIATION /00Z Sunday through Monday/...
Issued 554 PM MDT SAT AUG 29 2026

VFR. Scattered showers and isolated thunderstorms this evening
capable of 25-35 kt outflows, mainly southeast of a KREO-KBOI-
KSNT line. SCT to BKN clouds in the same area, clearing out
behind a cold front this evening. Surface winds: W-NW 5-15 kt
with local gusts up to 30 kt following a cold frontal passage.
Gusts decreasing overnight. Winds aloft at 10kft MSL:
W-SW 15-30 kt


KBOI...VFR. Scattered showers and isolated thunderstorms to the
south and east of the terminal this evening. A cold front
arriving around 03z will bring a period of NW gusts up to 25 kt.
Otherwise, surface winds will be NW 6-12 kt throughout the
period.


&&

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

OR...None.

&&

$$

www.weather.gov/Boise

Interact with us via social media:
www.facebook.com/NWSBoise
www.x.com/NWSBoise

AVIATION.....NF
SHORT TERM...JM
LONG TERM....DG