923
FXUS65 KGGW 192011
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
211 PM MDT Tue Aug 19 2025

.DISCUSSION...

KEY MESSAGES:
1) Dangerously hot temperatures are expected over NE Montana again
for Wednesday with high temperatures between 95 and 105 degrees.

2) A cold front Wednesday night will increase shower and
thunderstorm chances with cooler weather Thursday and beyond.

WEATHER PATTERN OVERVIEW:

Upper ridging extending over Montana will continue the very hot
conditions Wednesday. Highs Wednesday, the hottest temperatures
will be in the east with highs 100 to 105 which may end up being
hotter with prefrontal warming ahead of the cold front Wednesday
night. There is growing concern in the valley locations along the
Yellowstone River for example near Terry and Glendive that
excessive heat will be particularly dangerous where some places
may see highs above 105. Future shifts will have to carefully
weigh whether this merits an upgrade to Excessive Heat Warning,
especially given that this is the first significant heat spell in
some time.

In the short term, the ridge axis moves into the Dakotas tonight
and a wave in SW flow aloft will move across central Montana with
a few showers and thunderstorms that could clip northern Phillips
County Wednesday morning before moving into Saskatchewan.
Associated strong winds should miss NW Phillips.

Expect increasing showers and thunderstorms Wednesday night into
Thursday with a cold frontal passage. The northeast zones are in a
Marginal Risk for severe thunderstorms. Hail and strong winds are
the main threats, with timing being the evening hours.

Markedly cooler temperatures are then expected to settle into the
region later in the week.

FORECAST CONFIDENCE & DEVIATIONS:

NBM was used for much of the forecast cycle. Winds Wednesday and
Wednesday evening were blended to NBM90 behind the surface trough.

There is particular concern in the Yellowstone River Valley
Wednesday afternoon. Heat risk remains squarely at a 3 for much of
the area, but given that this heat is of significant impact
compered to recent conditions, effects could be somewhat
amplified.

&&

.AVIATION...
LAST UPDATED: 1925Z.

FLIGHT CAT RANGE: VFR.

DISCUSSION:
Hot conditions this afternoon and again Wednesday could lead to
Density Altitude issues. Otherwise, mainly dry but hot conditions
are expected through Wednesday.

Southeast winds this afternoon will becoming light and variable
Wednesday morning before becoming NW later in the day, with speeds
near 10-15 kts by afternoon. TFJ

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM MDT Wednesday for Central and Southeast
Phillips-Central and Southern Valley-Daniels-Dawson-Eastern
Roosevelt-Garfield-McCone-Northern Phillips-Northern Valley-
Petroleum-Prairie-Richland-Sheridan-Southwest Phillips-Western
Roosevelt-Wibaux.

&&

$$

weather.gov/glasgow