FXUS65 KBOI 030900

AFDBOI



Area Forecast Discussion

National Weather Service Boise ID

200 AM MST Tue Feb 3 2026



.SHORT TERM...Today through Thursday night...Upper level ridge 

will reach maximum amplitude Wednesday directly over our CWA. 

It will easily be the strongest ridge in the middle latitudes 

anywhere in the northern hemisphere. This will cause abnormally

warm daytime temperatures above 5500 feet MSL, with an intense 

inversion below that will maintain air stagnation in the

valleys.  We expect fog and low clouds to slightly increase 

next two nights but hi-res models don't yet have it. The ridge 

will begin to break down Thursday as the axis shifts slightly

to our east. Higher elevations will cool slightly but the 

inversion will continue in the valleys.



.LONG TERM...Friday through Tuesday...The upper ridge will 

continue to gradually break down and shift east this weekend, 

finally allowing our CWA to come under moistening southwest

flow aloft. On Monday a north Pacific cold front and supporting

upper trough will come inland with a 50-70 percent chance of 

rain and snow in our CWA (highest chance in northern areas), 

and just as important, mixing winds and a likely end to the 

inversion.



&&



.AVIATION...VFR, except local IFR in patchy fog/stratus in the 

lower Treasure Valley (KONO and KEUL), and near KMYL until 16Z.

Top of surface-based inversion near 5500 feet MSL. Surface winds:

Variable less than 8 kt. Winds aloft at 10kft MSL: NW 15-20 kt.



KBOI...VFR. Cirrus clouds. Surface winds: SE less than 6 kt.



&&



.AIR STAGNATION...Current Air Stagnation Advisory has been 

extended until 5 AM MST Monday morning. The inversion will 

gradually weaken Saturday and Sunday, and a cold front Monday 

should be strong enough to break the inversion and provide 

enough mixing wind to scour the stagnant air out of the valleys.



&&



.BOI WATCHES/WARNINGS/ADVISORIES...

ID...Air Stagnation Advisory until 5 AM MST Monday 

     IDZ012-014-016-033.

OR...Air Stagnation Advisory until 5 AM MST /4 AM PST/ Monday 

     ORZ062>064.



&&



$$



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SHORT TERM...LC

LONG TERM....LC

AVIATION.....LC

AIR STAGNATION...LC