textproduct: Great Falls

KEY MESSAGES

- Warmer and drier conditions continue through Tuesday.

- The next wave of widespread showers and isolated thunderstorms arrives Wednesday.

- A cold front late Wednesday into Thursday will transition rain to snow, keeping cooler conditions through the weekend.

DISCUSSION

/Issued 123 PM MDT Sun Apr 19 2026/

- Meteorological Overview:

Upper-level ridging continues across the region through the beginning of the week. Increasing southwest flow aloft through Wednesday will continue to warm up temperatures to at or near record highs by Tuesday. Dry weather continues through Tuesday, though increasing moisture and warm air advection brings a low end chance for a shower near the higher terrain. Increasing southwest flow aloft will also bring breezy winds to Southwest MT Tuesday. The breezy, warm, and dry conditons (the hot, windy, dry index are creeping into the 95th percentile and afternoon humidities drop into the teens) brings a concern for elevated fire weather conditions Tuesday across Southwest MT. However, the "green-up" with some of the vegetation should help moderate any fire spread a little bit.

A bigger, open-wave trough along the Pacific coast moves into the region beginning Wednesday, with another trough moving south from British Columbia. A few waves of precipitation will move through as a result. The first being scattered showers and isolated thunderstorms forming ahead of the cold front passage Wednesday afternoon and evening. Widespread precipitation arrives along the front late Wednesday into Thursday morning. Cold air advection lower snow levels to the lower elevations by Thursday morning. Models start to diverge greatly with this mid week system with how they want these two troughs to evolve/interact. This results in a big spread in precipitation amounts and impacts. Gusty winds wrapping around the low pressure system late Wednesday into Thursday morning looks to bring windy conditions to the North- Central MT plains/mountains.

Ensemble clusters do hint at some sort of a northwest flow aloft pattern following this system Friday and into the weekend. This pattern keeps cooler temperatures with additional chances for rain/snow.

- Forecast Confidence & Scenarios:

Thunderstorms Wednesday:

There remains some uncertainty in the extent of thunderstorm development Wednesday. Increasing cloud cover during the morning can limit overall thunderstorm evolution. So far models hint at Fergus and Blaine counties as the area with the best chances for thunderstorms. Gusty winds would be the main hazards if any stronger storms do develop.

Snow and Precipitation Heading Into Thursday:

There is a big spread in solutions heading into Thursday. There seems to be some differences in the precipitation amounts and the corridor of the heaviest . Most areas have a ~0.5" to ~1" spread in moisture amounts Wednesday through early Friday morning. Models are still flip floppy in the corridor of heavier precipitation and amounts in that corridor. Some solutions hone in on the Central MT mountains for north/northwesterly upslope snow Thursday, while other solutions hone in more towards the Continental Divide/SW MT mountains.

Another factor into different scenarios is the stronger winds aloft wrapping around the mid level low Thursday morning. Depending on the snowfall rates across North-Central MT, snowfall combined with gusty northwest winds can cause poor visibility, and will have to be something to monitor in the coming days. -Wilson

AVIATION

20/00Z TAF Period

VFR conditions persist through the TAF period with some higher level cloud-cover moving across the area tonight through Monday. Surface winds from the west to southwest will decrease and become somewhat variable later tonight through Monday morning before increasing some Monday afternoon. Hoenisch

PRELIMINARY POINT TEMPS/POPS

GTF 40 75 43 80 / 0 0 0 0 CTB 36 73 40 78 / 0 0 0 0 HLN 41 75 42 80 / 0 0 0 0 BZN 35 75 39 79 / 0 0 0 0 WYS 24 64 27 67 / 0 0 0 10 DLN 37 73 40 75 / 0 0 0 0 HVR 38 75 42 82 / 0 0 0 0 LWT 40 71 44 79 / 0 0 0 10

TFX WATCHES/WARNINGS/ADVISORIES

None.