FXUS65 KGGW 041921

AFDGGW



Area Forecast Discussion

National Weather Service Glasgow MT

121 PM MDT Mon May 4 2026



.KEY MESSAGES...



- Much cooler than normal temperatures through Tuesday night.



- Hard freeze expected Tuesday night.



- Another slow warm up is expected midweek with slightly above

  normal temperatures by the weekend. 



- Instability brings slight chances for showers and thunderstorms

  for the weekend.



&&



.DISCUSSION...



WEATHER PATTERN OVERVIEW:



Anonymously strong upper low that has dropped into south-central

Canada will be more like Jabba The Hutt this week as it moves

little, keeping northeast Montana under a northwest flow. The

cyclonic nature of it through tomorrow may bring snow showers late

tonight and Tuesday. Expect temps to remain well below normal with

highs mainly in the 40s Tuesday and readings dropping into the

lower 20s Tuesday night for many area, giving most a hard freeze.



The upper low drifts east a bit Wednesday allowing some warmer air

to move in with a continuation of limited moisture available for 

precipitation.



By late in the week, periodic shortwaves will pass through and 

bring scattered showers and thunderstorm activity, mostly favoring

elevated areas in the southwest zones. More persistent chances 

for precipitation look to return next weekend, with models 

beginning to hint at another shortwave trough at the end of the 

workweek. However, most ensemble members at this time show a 

tenth of an inch or less for rain amounts.



FORECAST CONFIDENCE & DEVIATIONS:



Deviation: 



Lowered temps Tuesday night, blending with NBM25,

given the area is under a surface high. Light winds and mainly

clear skies should lead to good radiational cooling.



Confidence is moderate or average for the extent of warming and 

further drying later this week based on advancement of upper 

ridging to the west. After midweek there is very little model 

agreement in the strength and location of troughing and closed 

lows. TFJ



&&



.AVIATION...

LAST UPDATED: 1900Z



FLIGHT CAT RANGE: VFR



DISCUSSION: Dry conditions are expected through Tuesday but an

isolated snow shower is possible late tonight. Brief MVFR

visibility is possible closer to cloud level.



WIND: NW decreasing to N around 10 kts by 06Z. TFJ



&&



.GGW WATCHES/WARNINGS/ADVISORIES...

Lake Wind Advisory until 7 PM MDT this evening for Central and 

Southeast Phillips-Central and Southern Valley-Garfield-McCone-

Petroleum.



&&



$$



weather.gov/glasgow