377
FXUS65 KBOI 290331
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
831 PM MST Fri Nov 28 2025

.DISCUSSION...
Broadly cyclonic flow in place across North America, and is
reinforcing a cold air mass from the northern Rockies into the
southern Appalachian region. Southwest Idaho is on the periphery
of this cold air mass, with surface observations across the
Snake Plain generally in the mid-upper 30s this evening. The
biggest concern late tonight and early tomorrow remains the
potential for fog. Latest hi-res model guidance and observation
trends suggest this is most likely along the I-84 corridor
between Boise and Twin Falls, into the Camas Prairie. Will
watch these trends closely if a widespread dense fog threat
develops. Otherwise, no precipitation is expected overnight,
with the next system poised to move into the region late
Saturday evening.

&&

.AVIATION...Areas of low stratus/fog likely to develop again through
Sat morning, though not as widespread as Fri. Localized VLIFR/IFR
possible. Mostly VFR conditions expected 16-17Z Sat as fog
dissipates with high clouds persisting. Chances of snow showers
increase by 30/06Z near KMYL/KBKE. Surface winds: variable less than
10 kt. Winds aloft at 10kft MSL: N 10-20 kt, becoming WSW 5-15 kt
after 30/18Z.

KBOI...Areas of vicinity fog/low stratus likely overnight, with a
30% chance of low visibilities/LIFR directly impacting the terminal.
Potential for fog decreases after 30/15Z with dry conditions
expected. Surface winds light and variable overnight, becoming
southeast around 10 kt late Sat morning. Sunday Outlook...

Sunday outlook...Widespread snow showers Sunday morning, with
generally light accumulations in the lower elevations. Periods
of low visibility likely leading to MVFR to LIFR in snow with
mountain obscuration. Surface winds: NW 5-15 kt with afternoon gusts
15-25 kt.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Sunday night...A cold front has
moved through the area and mixed out the fog in the lower
valleys this afternoon with breezy west to northwest winds.
Strongest winds will be in the Magic Valley with gusts to
35-40 mph this afternoon. Any lingering showers will taper off
this afternoon. Fog is forecast to redevelop in the valleys
tonight into Saturday morning, with the best chance coming along
the foothills in the Boise metro, to the Magic Valley, Baker
Valley and around Burns OR. Another system and cold front
arrives late Saturday night into Sunday morning. First snow of
the season possible for many valleys locations on Sunday morning
with a dusting of snow. Snow accumulations will be generally
under an inch in the valleys and 1 to 3 inches in the mountains.
Precipitation will taper off midday on Sunday with breezy
northwest winds during the afternoon and partial clearing.

LONG TERM...Monday through Friday...North-northwesterly flow
aloft on Monday will keep temps seasonal through the long
term, as most of the polar airmass is in the north-central
CONUS. Though, the position of the jet overhead will carry a
couple shortwave troughs through the area. The first arrives
Tuesday and Wednesday with precipitation chances 20-40% in lower
elevations and 60-70% in high elevations. Rainfall/liquid
equivalent forecast during this system is a trace to 0.03 inches
for lower elevations and up to 0.2 inches for higher
elevations. With snow levels at 3-4 kft MSL, locations above
that will see 0-2 inches of snow. Models split in the track of
the low afterwards, but the favored solution is to amplify the
shortwave into a closed low and then cut off low west of
California. This would wedge high pressure between the low and
the jet, pushing the storm track mostly north of the area. This
would keep skies cloudy as waves pass to north, but otherwise be
mostly dry. The GFS deterministic and a few ensemble members
keep the Tues/Wed low amplified but within the stream,
preventing development of a cut off low. This would push the
higher pressure further south and open up the possibility of
more active weather Friday and Saturday. Again, the cut off low
solution is more favored, but there is uncertainty about the
forecast later next week.

&&

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

&&

$$

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DISCUSSION...JR
AVIATION.....JR
SHORT TERM...KA
LONG TERM....JM