056
FXUS65 KBOI 092105
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
205 PM MST Sun Nov 9 2025

.SHORT TERM...Tonight through Tuesday night...A highly
amplified upper ridge will remain over the region through early
Monday, resulting in dry weather under mostly clear skies.
Temperatures will cool to near normal tonight. The upper level
ridge weakens significantly on Monday as an upper trough tracks
through the Idaho panhandle. This will be the warmest day, with
highs around 10 degrees above normal. 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.
However, the inversion will hold highs near normal across the
lowest elevations, where temperatures will be slightly lower but
still above normal. This can be seen in Monday`s forecast high
of 55 degrees for both Ontario and McCall. Precipitation remains
north of the area with the frontal passage Monday, with only
high clouds affecting the region. The ridge rebuilds northward
again on Tuesday, with the axis positioned east of the area,
allowing for increased southwesterly flow and warming aloft.

.LONG TERM...Wednesday through Sunday...Southwest flow will be
overhead to begin Wednesday, with the primary upper-level trough
axis moving closer to being onshore. Precipitation chances
begin in SE OR Wednesday evening, with SW ID being overnight
into Thursday. A west-to-east increase in PoPs will follow
during the day Thursday, with high PoPs sticking around through
Friday. The best chance for precipitation (60-80%) comes
Thursday through early Friday along the leading edge of the
upper trough/cold front. Wind gusts ahead and quickly following
this front will be 25-35 mph across southern Harney, Malheur,
and Owyhee counties. The main trough axis will move through by
late Friday, bringing NW flow aloft back in for Saturday, with
long range models hinting at lingering moisture and brief upper-
level ridging midday Saturday into Sunday. The trend of this
ridging will need to be monitored to determine precipitation
chances over the weekend. Snow levels will start around 8kft MSL
on Thursday, dropping to between 4500-6000 feet for Fri-Sat,
and 5000-6000 feet for Sunday. Temperatures begin the period
10-15 degrees above normal, will cool to near normal for Friday
through Sunday.

&&

.AVIATION...VFR. Surface winds: SE-E less than 12 kt, becoming
light and variable overnight. Winds at 10kft MSL: W-SW 5-15 kt.

KBOI...VFR. Surface winds: SE 4-10 kt.

&&

.AIR STAGNATION...Inversion will strengthen over the area
through Monday upper ridge brings quick warming aloft. This
will result in lowering mixing heights which reach a minimum of
roughly 1500-2000 feet AGL on Monday. Some improvement is
expected Tue/Wed after the passage of an upper trough brings in
cooler air aloft. While surface winds remain light, the NBM
shows mixing heights increasing to 2-3kft AGL Tue/Wed. The dry
air mass and lack of snow cover and will limit fog development
through this event. A pattern change later in the week will
replace the stagnant air mass with cooler and wetter conditions
Thur/Fri.

&&

.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...JDS
LONG TERM....CH
AVIATION.....CH
AIR STAGNATION...JDS