409
FXUS65 KGGW 232032
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
232 PM MDT Sun Aug 23 2026

.KEY MESSAGES...

- Severe thunderstorms begin this evening bringing strong winds,
  large hail, and heavy rainfall.

- Cold front tonight will bring gusty NW winds on Monday.

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


&&

.DISCUSSION...

WEATHER PATTERN OVERVIEW:
Upper ridge over eastern Montana overnight will move east today
while an upper trough moves in from the Pacific NW tonight.

Showers and thunderstorms will move through the forecast area
today as the ridge axis moves east and a weak shortwave ahead of
the upper trough moves 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 upper trough will knock down the ridge tonight 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 lightning, which may pose
a risk of fire starts.

Gusty southeast winds overnight will diminish this morning which
will allow the Lake Wind Advisory to expire 3 AM.

Cold front moves through the area tonight and will bring gusty NW
winds on Monday with cooler temperatures. A Lake Wind Advisory may
be needed for Fort Peck Lake on Monday.

Ridge rebounds starting on Tuesday in the wake of the departing
trough to bring dry conditions with temperatures slightly above
normal.

FORECAST CONFIDENCE & DEVIATIONS:
Made tweaks to PoPs and thunder chances today and tonight. No
other changes to NBM. Confidence for storm chances is high today
and tonight, though timing, severity and exact location of
strongest storms remains uncertain.


&&

.AVIATION...
UPDATED: 1930Z

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

DISCUSSION: After 00z this evening, showers and thunderstorms
will move east through the area tonight. Some storms today and
tonight could become severe with large hail and wind gusts over 50
knots.

WINDS: East to SE at 5 to 15 knots most of today becoming variable
late this afternoon and remaining variable at 10 knots or less
tonight. Any thunderstorm that passes over TAF sites could have
strong, erratic wind gusts.


&&

.FIRE WEATHER...
Seasonably hot temperatures with a mix of wet and dry
thunderstorms are expected through tomorrow. Strong to severe
thunderstorms this afternoon will bring gusty, erratic winds and
frequent lightning. 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 from 10 AM to 9 PM MDT Monday for Central and
Southeast Phillips-Central and Southern Valley-Garfield-McCone-
Petroleum.

&&

$$

weather.gov/glasgow