480
FXUS65 KBOI 032143
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
243 PM MST Wed Dec 3 2025

.SHORT TERM...Tonight through Friday night...The atmosphere is
expected to direct a system up and over the ridge of high
pressure to our west beginning mid day Thursday through the
remainder of the short term period. Current satellite depicts a
broad swath of moisture ahead of this Pacific system, and model
data is in good agreement that widespread precipitation is
expected. Guidance hints that precipitation will arrive in
eastern Oregon by mid day Thursday then into southwest Idaho by
mid/late afternoon. Snow levels will initially be near valley
floors early in the day, rising to above 5500 feet overnight
into early Friday. There exists uncertainty with how long the
low level cold pool will remain in place across the Treasure
Valley and Weiser Basin. This could push back the changeover
from snow to rain in these areas. Guidance suggests a 10% chance
of 0.1 inches of snow for the Lower Treasure Valley and a 30%
chance of at least 0.5 inches of snow for the Weiser Basin.
Current guidance does not include accumulating snow in other
lower valley locations, such as the Upper Treasure Valley of
Idaho, but the chance of snow falling is above 60%. By early
Friday morning all areas below 5500 feet will have transitioned
to rain. For the mountain valleys, including the Long Valley of
Idaho, guidance suggests a 30% chance of greater than 4 inches
of snow late Thursday through the afternoon Friday. Travelers
along Highway 55 and Highway 21 in southwest Idaho should be
prepared for winter conditions. We will be monitoring for the
need to issue a winter weather related advisory for portions of
the central mountains of Idaho.


.LONG TERM...Saturday through Wednesday...Unsettled conditions
will continue through the weekend and into early next week as
moisture continues to stream over the top of the Pacific ridge
of high pressure. There is strong agreement amongst ensemble
model data that two periods of mountain snowfall are possible,
one Saturday through Sunday Night, and the second Tuesday into
mid week. Snow levels are expected to linger between 4500 and
6000 feet this weekend, before rising to around 7000 feet by
Tuesday. Travelers and recreators should anticipate winter-like
conditions in the mountains and along mountain roadways during
this period.


&&

.AVIATION...Areas of IFR/LIFR fog/low stratus tonight into early
Thursday morning, mainly near KBNO, mountain valleys, and north of
the Western Magic Valley. Otherwise, VFR conditions. Surface winds:
W-NW 5-10 kt, becoming light and variable overnight. Winds aloft
at 10kft MSL: N/NW 10-20 kt.

KBOI...VFR. A 15% chance of MVFR/IFR fog/low stratus Thursday
morning, with a higher chance along the foothills. Surface winds: NW
around 5 kt, becoming light and variable overnight.

&&

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

&&

$$

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SHORT TERM...MC
LONG TERM....MC
AVIATION.....CH