textproduct: Great Falls

KEY MESSAGES

- Cooler and wetter conditions are expected to continue through Monday with drier and mild conditions on Tuesday.

- Warmer temperatures expected mid to late week.

- Potential for another storm system arriving this weekend.

UPDATE

/Issued 846 AM MDT Sun Jun 21 2026/ 845 AM Update...Updated forecast is out. Just adjusted pop/sky conditions towards current trends as showers have diminished this morning. Showers/thunderstorms will redevelop this afternoon as airmass becomes a bit unstable. The rest of the forecast is on track. Brusda

/Issued 130 AM MDT Sun Jun 21 2026/

Strong pressure rises in wake of a cold front combined with a barrier jet along and west of the I-15 corridor is helping to support strong and gusty northwest to north winds over portions of the plains early this morning. These winds will gradually subside through sunrise and spread further south and east across the remainder of North Central through Southwest Montana. The forecast has been updated to reflect the these trends. - Moldan

DISCUSSION

/Issued 100 AM MDT Sun Jun 21 2026/

- Meteorological Overview:

A relatively weak disturbance will track along the Canadian border through Sunday maintaining the cooler temperatures and introducing another chance for afternoon showers and thunderstorms mainly across North-Central Montana. This disturbance slowly makes its way east Monday and Tuesday leaving our area in northwesterly flow during this time. Temperatures will remain near to below average across the region with precipitation chances continuing through Monday evening.

Starting Wednesday, upper-level ridging starts to build over the western CONUS allowing for a warm up that is expected to last through the remainder of the work week. There is moderate agreement in another storm system arriving next weekend, although the finer details of how it will track across our region remain unclear at this time.

- Forecast Confidence & Scenarios:

Sunday/Monday Showers: Generally light precipitation is expected with any shower or thunderstorm that develops. There could be a couple that produce wind gusts in excess of 45 mph but otherwise the threat for strong storms is very low through the start of the week. The highest precipitation chances will be north of a line between Helena and White Sulphur Springs with accumulation amounts generally expected to stay under 0.10".

Thursday/Friday Heat: On Thursday there is a greater than 70% chance for highs exceeding 80 degrees across the lower elevations. Additionally, there is a 60% chance for some locations including Great Falls, Fort Benton, Helena, and Bozeman exceeding 85 degrees on Thursday. Friday currently looks to be slightly cooler with a 60% chance for highs exceeding 80 degrees along the lower elevations and a 50% chance for highs exceeding 85 degrees across portions of Chouteau and Fergus county as well as the Gallatin Valley. -thor

AVIATION

21/18Z TAF Period

Expect increasing clouds this afternoon, along with scattered showers/thunderstorms developing. Expect mainly showers after 06z, with most of the precipitation then falling over the eastern portions of the CWA later tonight and through Monday morning. Mountains/passes could be obscured at times this evening through Monday morning. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 74 48 66 44 / 10 20 30 10 CTB 69 44 62 40 / 20 50 10 0 HLN 80 51 72 45 / 0 0 20 10 BZN 78 46 74 42 / 0 20 20 10 WYS 70 38 74 36 / 10 30 0 0 DLN 77 46 77 42 / 0 10 0 0 HVR 75 47 69 44 / 0 50 30 10 LWT 71 45 63 40 / 10 40 50 10

TFX WATCHES/WARNINGS/ADVISORIES

None.