textproduct: Great Falls

KEY MESSAGES

- Widely scattered shower and thunderstorm activity develops over southwest Montana this afternoon and evening.

- A trough and attendant cold front dives southward tonight into Monday and brings a cool and showery start to the workweek.

- Milder and drier conditions return for the second half of the week, but passing fronts may bring some shower and thunderstorm activity and brief cool downs, especially heading towards next weekend.

DISCUSSION

/Issued 1157 PM MDT Sat May 2 2026/

- Meteorological Overview:

Dry northwesterly flow aloft will bring one more day of mild and generally dry condtions before a stronger trough and attendant cold front dive southward tonight into Monday. The primary concern will be dry and breezy conditions over the plains and isolated shower and thunder activity over southwest MT.

The cold front will cross the Canadian border this evening, clear much of central MT by dawn, and then move into the southwest Monday morning. Winds will shift northerly behind the front and showers and higher mountain snow will increase in a north to south fashion. Colder air aloft moves in on Monday and will support widely scattered rain, snow, and graupel showers at all elevations, especially over central/north-central MT. A secondary shortwave dives southward on Tuesday and drops H700/H500 temperatures as low as -15C/-30C over the eastern portions of the forecast area. This will reinforce the well below average temperatures and offer additional snow shower activity.

This system moves out by the mid-week period with northwesterly flow aloft returning for much of the remainder of the week. Overall, this will bring drier and milder conditions; however, weak troughs will periodically pass through and bring scattered shower and thunderstorm activity, especially on Thursday. Ensembles remain in agreement with a broader trough moving in next weekend for cooling temperatures and increased rain/mountain snow. Similar to some of the previous storms this spring, lesser defined and smaller scale forcing within this trough add forecast uncertainty in terms of precipitation amounts and timing. - RCG

- Forecast Confidence & Scenarios:

Gusty northerly winds tonight into Monday with showery and cool conditions through Tuesday...

The initial concern following tonight's cold frontal passage will be gusty northerly winds, especially over the plains and then the narrow north to south oriented valleys of central and southwest montana. These areas will have the greatest risk (50 to 70%) for wind gusts over 40 mph, highest in the Townsend area southward to Three Forks followed by Judith Gap, and the Dillon/Ennis areas. The front will cross the Canadian border by 8 pm this evening, clear much of central MT by the pre-dawn hours, and then move into the southwest Monday morning. The winds will begin diminishing by Monday evening for northern areas, but will continue through Tuesday in southwest Montana.

precipitation will be scattered in nature with snow and graupel showers down to the valley/plains by Monday afternoon. Impactful accumulations are generally not expected aside from a dusting to around an inch over the higher terrain of central and southwest MT. Of course there will be instances with heavier showers reducing visibility and temporarily leaving localized slushy accumulations. Increased instability will also bring a few thunderstorms, mostly in the afternoon and early evening. Temperatures will generally run around 10 to 15 degrees below average with freezing overnight temperatures. A secondary trough passage with cold air loft will maintain the cool showery conditions through Tuesday evening and near to below freezing AM temperatures through Wednesday. - RCG

AVIATION

03/06Z TAF Period.

Widely scattered showers tracking E/SE across central MT may affect the KLWT terminal through 10z with a lower-VFR cloud ceiling and brief erratic wind gust. Otherwise, VFR conditions prevail through Sunday with variable high level cloud-cover under west to northwest flow aloft. Surface winds remain generally light through Sunday morning with breezy west to northwest winds developing Sunday afternoon at most terminals. Hoenisch

PRELIMINARY POINT TEMPS/POPS

GTF 74 43 54 33 / 0 30 30 10 CTB 73 40 53 30 / 0 10 20 0 HLN 75 43 57 33 / 0 10 30 10 BZN 71 39 57 28 / 10 10 30 20 WYS 64 31 59 26 / 30 30 30 20 DLN 70 40 61 31 / 10 10 20 10 HVR 76 40 56 28 / 0 30 30 0 LWT 69 38 50 28 / 0 30 50 20

TFX WATCHES/WARNINGS/ADVISORIES

None.