151
FXUS65 KGGW 301846
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1246 PM MDT Wed Sep 30 2026

.KEY MESSAGES...
- The first major frost of the season is possible in some
  locations along valley bottoms Thursday morning.

- Coolest day will be tomorrow (Thursday) with a warming trend
  through early next week.

&&

.DISCUSSION...
Synoptic Setup: A cold front is dropping south across Montana
this afternoon. Quite a difference in conditions north of the
front this afternoon with clouds, scattered showers and temps in
the 50s over the northern zones with 60s and 70s to the south with
more sunshine.

Models did not pick up today`s precipitation very well. The
strength of the jet stream could have been the culprit and
sometimes models struggle with shoulder season (Spring and Fall)
events.

Tonight, clearing is expected with surface high pressure dropping
in from the Canadian prairies. There could be enough radiational
cooling that sends temps to near freezing in a few locations. But
midlevel clouds late could save some locations.

A subtle shortwave at the mid levels is expected to move through
the southern zones early Thursday and kick off a few stratiform
showers. Temps will be quite cool Thursday with surface high
pressure in place and should be the coolest day in this forecast
period. Frost has the potential again for Thursday night and
Friday but it looks like clouds could keep temps from plummeting.

Saturday into Monday: Surface high pressure over the Canadian
prairies looks to be in place this weekend with flow becoming full
NW. This will keep daytime temps near normal with dry conditions.

Monday night onward: Ensembles show a ridge building into the area
for dry conditions and above normal temps.

FORECAST CONFIDENCE & DEVIATIONS:
Deviations to NBM:

- Lowered temps tonight toward NBM10.

Many changes were made this morning to mainly raise pops and lower
temps. TFJ

&&

.AVIATION...
LAST UPDATED: 1900z

FLIGHT CAT RANGE: VFR

DISCUSSION: Clouds and rainshowers are expected to clear out this
afternoon then clouds return from the west after 06z tonight. Any
rainshowers are expected to remain south of the TAF/Airports
Thursday morning.

WIND: NW winds of 10-15 kts this afternoon become light N then
light and variable later tonight, continuing through Thursday. TFJ

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/glasgow