textproduct: Great Falls

KEY MESSAGES

- Very warm temperatures through the week with the hottest temperatures expected across the Northern Plains.

- Daily chances for showers and thunderstorms through the week. A few may become severe with the main threat being strong wind and hail.

DISCUSSION

/Issued 520 AM MDT Tue May 26 2026/

- Meteorological Overview:

Well above normal temperatures will continue through the rest of the week with highs remaining above 80 through at least Friday. The upper-level trough will migrate south this afternoon with the associated low starting to become more cutoff by Thursday morning. Throughout the rest of the week it will largely remain in this area, ejecting multiple shortwaves out towards Montana which will allow for daily chances for showers and thunderstorms. There is a chance a few storms may turn severe with the primary threat being strong winds and a secondary threat of hail.

- Forecast Confidence & Scenarios:

Heat this Week:

Tuesday is generally expected to be the hottest day across the region with many lower elevation locations reaching the upper 80s to upper 90s.

The main concern with Tuesday through Wednesday is that across northern Blaine county the overnight lows are only expected to dip down into the mid 60s which when sandwiched between two mid to upper 90 degree days could create additional heat stress for those living in the area. Considering the potential impacts, the decision was made to put northern Blaine county in a Heat Advisory through Wednesday.

Additional locations across North-Central Montana are near advisory criteria but given that there is enough confidence in temperatures cooling off sufficiently overnight, no additional zones were added at this time. But folks in Hill and Chouteau counties should be prepared for very warm temperatures and the potential threat for heat-related illnesses, especially for those spending a significant time outdoors. Additionally, there are heat-related concerns along the Upper Missouri Breaks such that anyone recreating in that area should be prepared for poor overnight temperature recovery, particularly along the lower valley which could cause additional stress if recreating.

Warm temperatures will continue across North-Central Montana through the rest of the work week. For now, given the levels of uncertainty with how hot it will get each day and how cool it will get each night, no additional products will be issued at this time. But folks should be prepared for the longest stretch of 90+ degree weather we have had so far this year.

Thunderstorms Chances this Week:

For Tuesday afternoon, there is some persisting uncertainty as to how moist it will get and whether the moisture will arrive in time to impact convective development. The moisture profile generally looks better Wednesday through Friday as the southerly flow continues to work some moist air into the region. Throughout this week the bulk of the uncertainty will revolve around whether the highest instability is able to overlap with the highest shear which would create a higher potential for severe weather. In the case where shear remains lacking, there is a concern that storms may still form but without a driving force they may linger over an area for too long and become more of a flash flood threat. -thor

AVIATION

26/18Z TAF Period

Widely scattered showers and thunderstorms will lift northward through southwest MT this afternoon before moving into central/north-central MT by this evening. The primary hazard with today's activity will be localized wind gusts, generally between 30 and 50 kts, highest over the plains and along the Rocky Mountain Front. VFR conditions are generally expected, but there will be an increase of low VFR clouds this afternoon, tonight, and again on Wednesday. Even through the convective wind threat decreases tonight, at least isolated shower activity will persist well into the overnight hours tonight. Then there will be a resurgence of widely scattered showers and thunderstorms again on Wednesday. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 90 55 85 56 / 30 70 30 30 CTB 89 54 82 52 / 40 70 50 50 HLN 85 51 84 52 / 60 70 40 30 BZN 79 45 83 46 / 60 50 40 20 WYS 69 37 79 39 / 80 50 40 10 DLN 73 43 79 46 / 80 50 30 20 HVR 97 61 95 55 / 10 40 30 30 LWT 89 53 85 52 / 20 50 20 30

TFX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 9 PM MDT Wednesday for Hill County-Northern Blaine County.