FXUS65 KMSO 051921

AFDMSO



Area Forecast Discussion

National Weather Service Missoula MT

121 PM MDT Wed Aug 5 2026



.DISCUSSION...



KEY MESSAGES:



-  Chilly mornings, hot afternoons with gradual warming trend 

   through the week.



-  Smoke will continue to impact the region until further notice.



-  Ridge of high pressure flattens heading into the weekend.

   Elevated and localized near-critical fire weather expected. 



A ridge of high pressure will continue to build over the western

U.S. maintaining warm, dry and stable conditions. Strong

radiational cooling under dry, "clear" (but smoky) skies allowed

Kalispell to set a record low of 38 degrees this morning. This

cooling is creating sharp nocturnal valley inversions which can

aid in trapping smoke near the surface worsening air quality and

visibility during the morning hours. Conversely, thermal belts on

mid-slopes and ridges will keep conditions warm and dry with

increasingly poor overnight humidity recoveries (25-35% range), 

contrasting with excellent recoveries in deep valley bottoms. 



Afternoon heating will remain a double-edged sword allowing us to

mix into cleaner air aloft or any thicker plumes that develop 

from regional wildfires and get transported overhead. Current 

high-resolution smoke modeling indicates heavier near-surface 

smoke concentrations peaking Thursday afternoon in the near-term.



Temperatures warm back into the 90s (or warmer) for many lower 

elevations by Friday and Saturday. As the ridge begins flattening

into a more zonal flow this weekend, afternoon surface winds will

increase. While synoptic winds currently look too marginal for

Fire Weather / Red Flag highlights during any given specific period

at this time, high temperatures, low humidity values, breezy

conditions, and low fuel moisture will continue to keep fire 

weather elevated if not near- critical. 



A slight uptick in available moisture riding the periphery of the

overhead ridge may introduce very slight chances for elevated 

convection from Friday through the weekend particularly across 

southwest Montana. Incredibly dry surface humidity could easily 

drive localized erratic outflow potential into the 30-50 knot 

range with a risk for new lightning ignitions.



Looking into next week, there is low confidence in a slow uptrend

of available moisture, but no widespread wetting rains are 

expected. A major Pacific NW closed low scenario will ultimately 

be required to induce a rapid downtrend in prevailing fire weather

and resultant smoky conditions. 





&&



.AVIATION...Increasing afternoon density altitudes are

anticipated with warming trend through the rest of the week.

Surface winds remain light and mostly diurnally/terrain driven

with stable conditions under a ridge of high pressure. Smoke plume

watch continues across the airspace. MVFR visibility conditions

are anticipated to develop in NW Montana through the day on

Thursday particularly around KGPI, and to a lesser extent KMSO. 



&&



.MSO WATCHES/WARNINGS/ADVISORIES...

MT...None.

ID...None.

&&



$$