FXUS65 KBOI 030339

AFDBOI



Area Forecast Discussion

National Weather Service Boise ID

839 PM MST Mon Feb 2 2026



.DISCUSSION...A weak system will bring light showers to WA and 

northern ID tonight, with a slight chance of showers mainly

north of a line from Baker City OR to McCall ID. An upper level

ridge will strengthen over the next several days and low clouds

and fog are more favorable to develop in the lower valleys after

tonight. Current forecast on track with no updates.



&&



.AVIATION...Mainly VFR this evening and overnight. Patchy freezing 

fog/low stratus returning overnight in sheltered mtn valleys and in 

the lower Treasure Valley (KONO and KEUL). MVFR/LIFR and mtn 

obscuration in fog/low stratus. Surface winds: Variable up to 10 kt. 

Winds aloft at 10kft MSL: W-NW 10-20 kt. 



KBOI...VFR with some high clouds overnight. A lower stratus deck may 

develop overnight, but conditions remain VFR. Surface winds: Light 

and variable, but leaning SE. 



&&



.PREV DISCUSSION...

SHORT TERM...Tonight through Wednesday night...

Upper ridging building into the area will continue to promote

stagnant, inversion conditions over the region. This also means

dry air with generally light winds, and no sign of precipitation

beyond this evening after a weak system ejects eastward. A

near-persistence forecast is in store, with high temperatures

peaking in the low 50s each day across lower elevation valleys,

and falling to near or below the freezing mark each morning.

Patchy fog is also possible each morning, especially in the

lower Treasure Valley and central Idaho mountain valleys. The

strength of the ridge will only increase into Wednesday, with

model guidance suggesting 582-585 dm 500 mb heights - close to a

record for the date per the SPC sounding climatology. 



LONG TERM...Thursday through Monday... High pressure is the name of 

the game through the end of this week. As has seemed to be the 

pattern of choice so far this winter, an amplifying ridge over our 

area and a deepening closed low near the Baja Peninsula will make 

way for a rex block. This will keep the day to day forecast very 

similar to each other with valley inversions and stagnant 

conditions. Valley fog/low stratus will be the the only hazard 

through the coming week. While temperatures will be above normal 

area-wide, valley cold pools will help limit lower elevation daytime 

highs each day. Through sunday, the current forecast carries daytime 

highs below the NBM 25th percentile. 



The door will start to open for a more unsettled pattern late this 

week as the closed low near the Baja Peninsula begins to re-embed 

into the main flow aloft. At the same time, the trough that has been 

over the Hudson Bay will begin to propagate east. Deterministic and 

model ensembles are in good agreement of a longwave trough moving 

over the western CONUS late this week/early next week. This trough 

will usher in cooler temperatures increased precipitation chances, 

and will break up the inversion. 



&&



.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 

     ORZ062>064.



&&



$$



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DISCUSSION...KA

AVIATION.....JY

SHORT TERM...JR

LONG TERM....NF