textproduct: Great Falls

KEY MESSAGES

- Trending warmer through Tuesday, with most areas remaining dry.

- Breezy Tuesday into Wednesday ahead of and behind a cold front.

- Seasonable temperatures to close out the week, with increasing opportunities for afternoon and evening showers and thunderstorms toward the weekend.

UPDATE

With clear skies, light winds, and seasonable temperatures, the forecast remains on track and no update is needed this evening. Ludwig

DISCUSSION

/Issued 522 PM MDT Sun Jun 14 2026/

- Meteorological Overview:

High amplitude ridging centered along the Pacific coastline is resulting in a northwesterly flow aloft across the region this afternoon. This ridging slowly slumps/become flattened heading into the week, eventually resulting in a breezier stretch Tuesday into Wednesday. Although the ridging is in place nearby, the nature of the northwesterly flow aloft is not particularly anti-cyclonic in nature. Weak perturbations overtopping the ridge will dive southeast across the region and result in a few showers tonight into early Monday in the vicinity of Havre, and then again across the Hi-line and vicinity Monday afternoon and evening. The timing in the afternoon and evening across the Hi-Line Monday will be more favorable for thunderstorm development, though instability isn't looking that impressive at this time.

More active weather moves in as the ridge is flattened Tuesday. Initial impact will be for a warm and breezy day Tuesday ahead of a cold front. The strongest winds aloft don't look to arrive til later afternoon Tuesday, which mutes confidence in any higher end winds materializing. As these stronger winds aloft arrive, the cold front begins to push in from north to south across the region late afternoon. There looks to be enough instability around to result in a few showers and thunderstorms along and behind the front over the plains Tuesday evening into Tuesday night. Should instability end up on the higher end of the envelope, a few thunderstorms capable of producing at least small hail Tuesday night near the Hi-Line would be a reasonable expectation.

Heading into Wednesday the brisk winds aloft begin to exit, but hold on over the plains east of US-87. Daytime heating and sufficiently cool air aloft will result in some showers activity, which would help mix some of the stronger winds to the surface. Regardless of the potential for stronger winds, Wednesday does look to be breezy at the least.

Northwesterly flow aloft largely persists to close out the week. While neither of Thursday or Friday have overwhelming support for showers and thunderstorms, weak waves moving through the flow aloft would support at least isolated showers and thunderstorms those two days.

Several weaker troughs moving in across the west this weekend will result in at the least a cyclonic nature to flow aloft. This will support better coverage of showers and thunderstorms. Should one of these waves trend stronger, a few stronger thunderstorms would not be unreasonable this weekend. -AM

- Forecast Confidence & Scenarios:

Timing of wind Tuesday:

The leading edge of the strongest winds aloft arrives Tuesday afternoon. Given the narrow temporal window for the stronger winds to materialize near the Rocky Mountain Front, and that there is potential for a the Canadian front to undercut westerly winds, a High Wind Watch is not being issued at this time. Should the winds pick up quicker and the cold front arrive a bit later, a High Wind Watch may become necessary.

Risk for hail Tuesday night:

The most aggressive guidance Tuesday night features MU CAPE on the order of 500 J/Kg or so across the Hi-Line. Should this materialize, ample westerly flow aloft would result in enough shear for at least briefly organized thunderstorms. Large hail would be the main concern should a stronger storm develop.

Gusty showers Wednesday:

Lingering flow on the order of 40-50 kts aloft look to overlap with some weak instability Wednesday afternoon east of US-87. Any showers that form would possess the ability to mix these stronger winds to the surface. Given the coverage of showers is questionable, it is too early to determine how impactful Wednesday will be in this area.

Thunderstorms this weekend:

Ensembles are favoring easterly winds over the plains this weekend into much of the following week. This is typically associated with a more active period of thunderstorms across the region. Those with outdoor interests should remain aware of the risk for stronger thunderstorms beginning this weekend. -AM

AVIATION

15/00Z TAF Period

VFR conditions will prevail throughout the entire 1500/1600 TAF period, with generally light and variable winds at any given terminal across Southwest through North Central Montana. An isolated rain shower can't be ruled out at the KHVR terminal between 09-18z Monday, but CIGS would only fall to around 10kft should a shower move overhead. - Moldan

PRELIMINARY POINT TEMPS/POPS

GTF 45 79 57 85 / 0 0 10 0 CTB 45 78 58 81 / 0 10 30 0 HLN 44 81 56 86 / 0 0 10 0 BZN 39 77 48 87 / 0 0 0 0 WYS 31 75 38 82 / 0 0 0 0 DLN 39 78 47 86 / 0 0 0 0 HVR 46 78 53 84 / 10 20 30 10 LWT 41 72 50 80 / 0 10 20 0

TFX WATCHES/WARNINGS/ADVISORIES

None.