textproduct: Great Falls

KEY MESSAGES

- Daily thunderstorm chances continue through Saturday, with the potential for some storms to be strong to severe.

- Increased temperatures continue today and tomorrow, with a cold front on Saturday cooling temperatures down this weekend through Tuesday.

- Widespread precipitation is expected this weekend across the region.

DISCUSSION

/Issued 1235 AM MDT Thu May 28 2026/

- Meteorological Overview:

A closed low continues to spin over California today and tomorrow, causing southerly flow aloft. This will advect warm moist air into the region, continuing the trend of warmer temperatures and daily convection for the next two days. Highs will be in the upper 80s to low 90s across the region today, remaining the same tomorrow with the exception of Southwest MT seeing slightly lower highs in the low to mid 80s. At this time, the strongest convection looks to occur tomorrow afternoon/evening, with chances for thunderstorms tapering off after Saturday.

On Saturday, the axis of the closed low moves northeast towards MT. At the same time, a small upper level trough moves into the Intermountain West, phasing with the closed low on Sunday. This pattern will bring ample moisture, with PWATs of 3-4 inches. As a result, widespread precipitation is expected this weekend across the region. A cold front on Saturday will also cool down temperatures through Tuesday, before weak upper level ridging on Wednesday brings them back up. -Dzomba

- Forecast Confidence & Scenarios:

Thunderstorms Today through Saturday

The models are showing 1,000-1,500 J/kg of CAPE across the region this afternoon, with the Euro and Canadian showing pockets of higher CAPE in Central MT. However, with dewpoints generally only reaching the low 50s in Central/North-Central MT, moisture will be a limiting factor in the strength of these storms. Overall, the thunderstorms this afternoon are not expected to be severe. However, some soundings are still showing a strong inverted V profile indicative of a dry surface layer, creating the potential for an isolated severe wind gust or two to occur. Storm motions may be a little bit slower towards Central MT which can increase the risk slightly for localized flash flooding over burn scars. Better instability and shear increases Friday, which will increase chances for marginal severe wind gusts and large hail. PWATs nearing an inch will bring a minor threat for localized flash flooding particular in burn scar areas/urban areas. Saturday's thunderstorm threat will mostly be focused to the Hill/Blaine/Fergus County areas.

Precipitation this Weekend

There is increased confidence with the precipitation this weekend, as the spread between models thins. Saturday through Sunday, there is an 85 to 95% chance for at least 0.25" of precipitation and an 80 to 90% chance for at least 0.5". However, there are still some slight differences for how the closed low phases with the new incoming trough, leading to an increased spread in the probabilities for higher amounts. There is a 60 to 80% chance for at least 1" of precipitation, and a 15% to 60% chance for 2" inches. Snow levels look to drop to above pass level, which can bring light, slushy snow accumulations to the higher peaks. -Wilson and Dzomba

AVIATION

28/12Z TAF Period

VFR conditions will prevail across all terminals during this TAF Period. This afternoon and evening there will be very isolated showers and thunderstorms across North-central, Central, and Southwestern Montana. At the KBZN, KHLN, KGTF, and KHVR terminals there is a 15% chance for showers and thunderstorms between 28/21Z and 29/06Z. At the KCTB and KLWT terminals there is a 20 - 40% chance for showers between 28/18Z and 29/06Z and a 15 - 25% chance for thunderstorms between 28/21Z and 29/06Z. All thunderstorms will produce frequent lightning and gusty, erratic winds. -IG

PRELIMINARY POINT TEMPS/POPS

GTF 90 57 89 56 / 20 30 20 50 CTB 89 54 85 53 / 50 40 20 30 HLN 91 56 87 53 / 20 20 30 60 BZN 90 48 85 47 / 20 20 30 50 WYS 84 40 78 39 / 10 0 20 30 DLN 87 47 81 46 / 10 0 10 50 HVR 94 57 94 55 / 20 20 20 40 LWT 88 52 87 50 / 30 20 40 60

TFX WATCHES/WARNINGS/ADVISORIES

None.