499
FXUS65 KBOI 270830
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
230 AM MDT Sun Sep 27 2026

.KEY MESSAGES...
- Virga and light rain today through early Monday, with highest
  rain chances across east Oregon and the west-central Idaho
  mountains.

- Warm and dry conditions expected Tuesday through next
  weekend, with max temperatures peaking Wednesday and Thursday.

&&

.SHORT TERM /Through Tuesday Night/...
Southeast Oregon and southwest Idaho reside under southwest
flow aloft this morning ahead of a weak trough over the West
Coast. This trough is spreading a swath of mid-level moisture
across the area today through early Monday, bringing cloudy
skies, widespread virga, and light rain. While precipitation is
expected to be sporadic as moisture expands northward, the
highest probabilities of measurable rainfall are over east
Oregon and west-central Idaho (20-40%) mainly in the afternoon
and evening...with lower chances (5-15%) elsewhere. Southwest to
northwest surface winds will become breezy this afternoon
across southeast Oregon and portions of the western Snake Plain.
As the trough heads eastward overnight into early Monday, the
moisture will also depart toward the east. As a result, skies
will begin to clear and temperatures will trend warmer for
Monday compared to previous days. Westerly flow aloft will
establish over the region beginning Tuesday, with dry and warm
conditions anticipated.

&&

.LONG TERM /Wednesday through Sunday/...
Forecast models depict a building ridge over the southwestern
U.S. from Tuesday through Thursday, driving lower-elevation
temperatures into the upper 70s/low 80s by Wed and Thu.
Thereafter, a weak shortwave trough will enter the Pacific
Northwest on Friday, briefly flattening the ridge and dropping
temperatures by a few degrees Friday through Saturday. Moisture
associated with this trough is likely to remain north, keeping
southeast Oregon and southwest Idaho in a drier airmass. The
ridge is expected to rebound on Sunday as the trough continues
east, supporting the return of above normal temperatures.

&&

.AVIATION /06Z Sunday through Monday/...
Issued 1225 AM MDT SUN SEP 27 2026

Mainly VFR with mid to high clouds. Isolated to scattered light
rain showers and virga will expand north across the area today.
Surface winds: variable less than 10 kt through morning,
becoming NW 5-15 kt with gusts to 25 kt east of KBOI after
Sun/21Z. Winds aloft at 10kft MSL: SW 10-20 kt.

KBOI...VFR. Virga or light rain in the vicinity through morning.
A 15% chance of rain reaching the ground at the terminal.
Surface winds: SE around 5 through morning, becoming NW 7-12 kt
this afternoon, with gusts to around 20 kt mid-afternoon
through early evening.

&&

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

OR...None.

&&

$$

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SHORT TERM...SH
LONG TERM....SH
AVIATION.....SH