FXUS65 KBOI 021040

AFDBOI



Area Forecast Discussion

National Weather Service Boise ID

340 AM MST Mon Feb 2 2026



.SHORT TERM...Today through Wednesday night...Skies have mostly

cleared, helping fog form in parts of the Lower Snake Plain.

Visibilities haven't dropped to less than 1 mile, however this

is likely to change in the coming nights. High pressure aloft is

helping build an inversion over the area, keeping air stagnant

near the surface and trapping particles and moisture. Fog this

morning will dissipate in the day giving way to a light haze,

before reforming with a wider extent tonight. This pattern will

continue through the short term as a blocking pattern sets in.

Temperatures remain mostly mild, but will cool in valleys that

see fog form overnight as cold air pools.



.LONG TERM...Thursday through Monday...High pressure,

inversions, and stagnant air continues through Friday morning.

This means continued morning fog and colder temps in valleys.

High elevations will be dry and mild. The synoptic pattern is

expected to change Friday evening as the cut off low driving the

blocking pattern weakens and rejoins the primary flow. While

models still disagree on exact timing, all show a zonal to

northwestly moisture flow moving overhead by Sunday/Monday. This

longwave troughing moving over the Northern Rockies is a good

indicator of unsettled conditions, precipitation, and colder

temperatures for all elevations in the long term. The transition

period Friday to Sunday means inversions may last longer than

Friday, we will wait for future model runs to come into

alignment on the inversion breakdown.



&&



.AVIATION...MVFR-IFR in the lower Snake Plain due to fog,

clearing by noon. Otherwise VFR this morning with some mid to 

high clouds continuing through the day. Fog is likely to reform

tonight. Surface winds: variable less than 8 kt. Winds aloft at

10kft MSL: W 10-15 kt.



KBOI...VFR with some mid and high clouds. Surface winds variable 

less than 5 kt, with weak NW winds this afternoon. 



&&



.AIR STAGNATION...An Air Stagnation Advisory remains in effect

through Friday morning in the Treasure Valley and Upper Weiser 

River Valley, and has been extended to the rest of the Snake

Plain. This is due to limited vertical mixing and light winds. 

Warming aloft Tuesday through Friday will make the inversion 

stronger in the valleys, likely leading to stagnant conditions

in the rest of the area by Wednesday.



&&



.BOI WATCHES/WARNINGS/ADVISORIES...

ID...Air Stagnation Advisory until 11 AM MST Friday 

     IDZ012-014-016-033.

OR...Air Stagnation Advisory until 11 AM MST /10 AM PST/ Friday 

     ORZ064.



&&



$$



www.weather.gov/Boise



Interact with us via social media:

www.facebook.com/NWSBoise

www.x.com/NWSBoise



SHORT TERM...JM

LONG TERM....JM

AVIATION.....JM

AIR STAGNATION...JM