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 1141 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 1141 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

22/00Z TAF Period

Mid-level cloudiness will continue across the region through the overnight hours with low-level cloudiness increasing across North-Central Montana as showers start to develop after 22/06Z and continue through Monday morning. The majority of the precipitation is expected across the eastern portions of the CWA including KHVR and KLWT, however, there is still a 10-20% chance that high-MVFR ceilings could encroach around KGTF and KCTB. Mountain obscuration will remain a concern through much of the period as Monday afternoon is expected to bring another round of isolated showers and thunderstorms to North-Central and Central Montana.

Across Southwest Montana, scattered to broken mid-level cloudiness will persist through the first half of the period with gradually clearing skies heading into late Monday morning. For any locations that are able to clear out sooner overnight, there is a low probability of fog developing. However, confidence was not high enough to include it in this round of TAFs. -thor

PRELIMINARY POINT TEMPS/POPS

GTF 48 66 44 72 / 20 30 10 0 CTB 44 62 40 70 / 50 10 0 0 HLN 51 72 45 76 / 0 20 10 0 BZN 46 74 42 76 / 20 20 10 0 WYS 38 74 36 78 / 30 0 0 0 DLN 46 77 42 77 / 10 0 0 0 HVR 47 69 44 72 / 50 30 10 0 LWT 45 63 40 67 / 40 50 10 0

TFX WATCHES/WARNINGS/ADVISORIES

None.