FXUS65 KGGW 190836

AFDGGW



Area Forecast Discussion

National Weather Service Glasgow MT

236 AM MDT Tue Aug 19 2025



.DISCUSSION...



KEY MESSAGES:

1) Dangerously hot temperatures are expected over NE Montana for

today and 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 lead to very hot  

conditions today and Wednesday. Highs today will be near 100 in

many areas. On 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, area of showers is following a weak shortwave

early this morning. The showers were weakening over Phillips

County at 08z as the wave moves across the ridge axis currently 

over eastern Montana. The showers are expected to dissipate before

sunrise. 



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.



Expect increasing showers and thunderstorms Wednesday night into

Thursday with a cold frontal passage. 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. Temperatures were 

nudged toward NBM50 for today and Wednesday high temperatures to 

account for pre- frontal compressional warming. 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: August 19, 2025 at 0830Z.



FLIGHT CAT RANGE: VFR.



DISCUSSION: 



An isolated shower south of Malta at 08z may hold together long

enough to move through KGGW early this morning. There will be some 

mid and high level clouds at times with mainly dry weather 

conditions today and tonight. Very hot temperatures above 100 

degrees for this afternoon and Wednesday afternoon could provide 

impacts to heat sensitive equipment.



WIND: Light and variable this morning becoming south to SE 5 to 

15 knots this afternoon and east to SE tonight.





&&



.GGW WATCHES/WARNINGS/ADVISORIES...

Heat Advisory from 10 AM this morning to 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