FXUS65 KGGW 222039
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
239 PM MDT Sat Aug 22 2026

.KEY MESSAGES...

- Typical mid to late August conditions are expected through the
  weekend with warm daytime conditions and comfortable nights.

- Increasing risk for isolated severe thunderstorms tomorrow
  afternoon bringing strong winds, large hail, and heavy rainfall.

- Warm and dry conditions resume next week as the western ridge
  rebounds.


&&

.DISCUSSION...

WEATHER PATTERN OVERVIEW:
Upper ridge over the northern Rockies will begin to slide east
today in response to a trough pushing into the Pacific Northwest.

Showers and thunderstorms are expected to develop overnight as the
ridge axis moves east and a weak shortwave pushes south through 
the ridge. Ample midlevel monsoonal moisture will begin streaming
into eastern Montana and with high PWATs possible, some storms 
could produce heavy rain. The Pacific NW trough will knock down 
the ridge on Sunday with another round of storms. Strong winds 
aloft will increase vertical wind shear and coupled with moist,
unstable air will bring increased severe risk. Any storms that 
develop may produce damaging winds and large hail. All 
thunderstorms have dangerous lightning, which may pose a risk of 
fire starts.
 
Southeast winds will also be increasing today ahead of the 
disturbance that will make conditions on Fort Peck Lake hazardous.
A Lake Wind Advisory is in effect until 3 AM tonight.

Ridge rebounds early next week in the wake of the departing 
trough to bring dry conditions with temperatures slightly above 
normal.

Fire weather is expected to be quiet as humidity will be on the
rise with winds this weekend. Otherwise, winds are expected to
decrease after the weekend and be generally light through the 
next seven days.

FORECAST CONFIDENCE & DEVIATIONS:
Increased PoPs and PoT following the upgrade to slight risk.
Confidence for timing of storm chances tomorrow is high, though 
severity and exact location of strongest storms remains uncertain.


&&

.AVIATION...
UPDATED: 1900Z

FLIGHT CONDITION: VFR. MVFR to IFR in stronger storms.

DISCUSSION: Clear, dry, and breezy conditions expected to 
maintain through the early evening. Beginning after 6Z an initial 
push of showers and isolated thunderstorms move west to east over 
TAF sites. After a brief lull during the overnight and early 
morning hours, scattered strong to severe thunderstorms look to 
impact western TAF sites around 0Z tomorrow and exit eastern 
sites after 4Z.

WINDS: SE at 10 to 20 kts, beginning to weaken by 6Z today. Low 
pressure system passes over around mid day tomorrow with winds 
becoming west. Any thunderstorm that passes over TAF sites will 
have strong, erratic wind gusts.

&&

.FIRE WEATHER...
Seasonably hot temperatures with a mix of wet and dry
thunderstorms are expected through Monday. Two rounds of showers 
and thunderstorms begin this evening with steadier showers will 
see wetting rains. Strong to severe thunderstorms in the afternoon
tomorrow will bring gusty, erratic winds and frequent lightning. 
Areas that didn't see rain the night before may be at a higher 
risk for lightning starts as fuels will continue to dry out with 
high temperatures and stronger winds tomorrow. Though min RH 
values in the 20-40% range and good overnight recovery will 
mitigate fire weather concerns. Warm and dry conditions are 
expected to resume Tuesday.


&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 3 AM MDT Sunday for Central and 
Southeast Phillips-Central and Southern Valley-Garfield-McCone-
Petroleum.

&&

$$

weather.gov/glasgow