490
FXUS65 KBOI 222050
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
150 PM MST Sat Nov 22 2025

.SHORT TERM...Tonight through Monday night...Another round of
stable conditions are expected overnight into most of Sunday as
flat high pressure remains in control. There is strong agreement
that low stratus and fog will develop overnight. The latest
guidance indicates a 60-80% chance of stratus/fog for the Lower
Treasure Valley of Oregon and Idaho and the Magic Valley, with
a 30-50% chance for the Baker and Magic valleys. There is
potential for dense fog with visibilities less than 1/4 mile in
the Lower Treasure Valley and eastern Magic Valley (30-40%
chance) by early morning Sunday.

A Pacific storm system is expected overnight Sunday into Monday,
with the majority of precipitation anticipated north of the
Snake River Valley in the central mountains. Winds will pick up
behind the system during the day on Monday as well. Snow levels
will generally be above 5000 feet with 1 to 3 inches possible.

.LONG TERM...Tuesday through Saturday...Unsettled conditions
prevail through the long term. Tuesday is looking to start out dry
but with increasing high clouds as mid-level moisture makes its way
around the ridge to our west. By late Tuesday/early Wednesday, the
bulk of the moisture advection will be overhead allowing for
increasing chances of precipitation chances of 20-70% across much of
the area, generally increasing as you move from south to north. Snow
levels start out at 2-3 kft MSL Tuesday night, so the Snake Plain
could see a wintery mix early Wednesday morning before snow levels
rise to 4-6kft MSL. Through the latter half of the week, there is
good model consensus of the ridge moving over our area. The area
will begin to dry out Thursday; however, A shortwave grazing our
northern zones late Thursday/early Friday will keep elevated
precipitation chances (20-50%) in Baker county, the west Central
Mountains, and Boise mountains. That shortwave, and the system
evolution following it, is helping mitigate air stagnation concerns
despite general ridging over our area.

Friday into the weekend, Confidence is increasing in a trough
digging down over our area. This trough is leading to elevated
precipitation chances (50-70%) across the majority of our area
Friday evening through Saturday. Uncertainty does, however, remain
regarding just how deep the trough will get. This is resulting in
some uncertainty with how much we will cool off over the weekend,
and how just low the snow level drops. Temperatures begin near
normal on Tuesday, increasing to 5-10 degrees above normal Thursday.
Temperatures will begin to cool off through the weekend, but as
noted earlier, uncertainty remains to what degree; for now, am
maintaining temps near normal for Saturday.

&&

.AVIATION...Areas of IFR/MVFR continuing early this afternoon in
Fog/Low stratus, continuing to improve to VFR. Fog/low stratus will
increase again overnight in mtn valleys and lower Snake Plain,
confidence decreasing from KBOI on east. resulting in IFR/LIFR
conditions lasting through the morning. Surface Winds: S-E 5-15 kt,
becoming variable overnight. Winds aloft at 10kft MSL: W-SW 5-20
kt.

KBOI...VFR conditions expected overnight. Although there is a slight
chance (15%) of fog/low stratus developing at terminal between
Sun/11z-Sun/17z. Confidence in development is low. Surface winds: SE
6-12 kt, decreasing to under 8 kt by Sun/00z.

&&

.AIR STAGNATION...Another round of stagnant air expected Sunday
with mixing heights only 1500 to 2500 feet above ground level by
mid afternoon. Improving conditions Monday as a trough of low
pressure moves through the region and winds shift to the
northwest.

&&

.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

SHORT TERM...MC
LONG TERM....NF
AVIATION.....NF
AIR STAGNATION...MC