412
FXUS65 KBOI 090342
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
842 PM MST Sat Nov 8 2025

.DISCUSSION...A strong upper level ridge will keep conditions
dry with high clouds moving overhead through early next week.
Tonight, dry air in place and a cool air mass will allow lows to
dip into the 20s and 30s across the area, with some sheltered
mountain valleys dipping into the 10s. The ridge axis will move
overhead on Sunday. This will bring several degrees of warming,
especially in the mountains as inversion conditions strengthen
in the valleys and limit warming. A light east to southeast
breeze will develop by Sunday morning. Forecast remains on track
and no updates this evening.

&&

.AVIATION...VFR. Few high clouds across E`rn OR and W`rn ID.
Surface winds: Variable or SE under 10 kt tonight. Winds aloft
at 10kft MSL: W-NW 5-15 kt.

KBOI...VFR. Surface winds mostly light and variable, becoming
SE 5-10 kt later tonight after 05Z.

&&

.AIR STAGNATION...High pressure aloft will bring a period of
more stagnant conditions to the region next week. A temperature
inversion will lower mixing heights to between 2-3kft AGL
Sunday, possibly dropping below 2kft AGL Monday and continuing
through Wed/Thur. There could be some improvement late Monday
into Tuesday with passage of a weak cold front. Light winds
will accompany lower mixing heights. The dry air mass and lack
of snow cover and will limit fog development.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Monday night...A highly amplified
upper ridge will remain over the western US through Sunday,
resulting in dry conditions under mostly clear skies. This will
also promote warming aloft, which will add another 3 to 5
degrees to high temperatures each day into Monday. The lower
valleys will be slower to warm up through this period due to an
inversion through at least Sunday. The upper level ridge
weakens significantly on Monday as an upper trough tracks
through the Idaho panhandle. There looks to be a strong enough
surface gradient for winds up to 15 mph to help mix and weaken
the inversion in the lower valleys Monday afternoon. Highs will
be around 10 degrees above normal on Monday, except across the
lowest elevations where temperatures will be slightly lower but
still near normal.

LONG TERM...Tuesday through Saturday...With an impending upper-
level trough coming into the Pacific Northwest, development of
a weak upper-level ridge Tuesday and early Wednesday will keep
temperatures warm for this time of season. Beginning midday
Wednesday, southwest flow will begin to overspread the area
ahead of the incoming upper-level trough. The trend over the
last few days keeps the trough coming in a bit slow, leading to
impacts from the associated cold front, precipitation, and wind
gusts from happening until afternoon/evening Thursday.
Precipitation chances start Wednesday evening in SE OR and early
Thursday morning in SW ID. The trend for precipitation
beginning should become later with future model runs.
Regardless, PoPs will rise west-to-east Thursday, with lower
elevations 20-50% chance and higher elevations 40-80% chance.
The best chance for precipitation areawide will happen Thursday
evening into midday Friday, however chances will remain from
Thursday through the extended. Snow levels will start out above
8kft MSL on Thursday, dropping to 5-6kft by Saturday as the
first trough passes. Temperatures hold around 10 degrees above
normal (lowest elevations excluded) through Thursday, with the
flip to a trough cooling temperatures to around normal starting
Friday.

&&

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

&&

$$

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DISCUSSION...ST
AVIATION.....JY
AIR STAGNATION...JDS
SHORT TERM...JDS
LONG TERM....CH