textproduct: Great Falls

KEY MESSAGES

- Breezy at times Wednesday afternoon with stronger winds possible around any thunderstorm that develops.

- Cooler and wetter conditions continue on Thursday with another chance for afternoon thunderstorms.

- More seasonable temperatures Friday and Saturday before cooling off again Sunday and Monday.

DISCUSSION

/Issued 1202 AM MDT Wed Jun 17 2026/

- Meteorological Overview:

Breezy conditions are expected on Wednesday across portions of Central Montana but to a lesser extent than what was observed on Tuesday. Northwesterly flow will remain in place through Thursday bringing daily chances for afternoon showers and thunderstorms.

On Friday, upper-level ridging starts to build bringing a day of warmer and drier conditions to the region. Saturday into Sunday the ridge flattens a bit with allows for a brief period of precipitation before building back over the western CONUS through at least the middle of next week.

- Forecast Confidence & Scenarios:

Gusts up to 35 mph are possible Wednesday afternoon, especially along the Hi-Line and Central Montana east of a line between Inverness and Geyser. Afternoon instability is enough that isolated thunderstorms are possible across the Northern Plains. With DCAPE values in the 400-800 J/kg range, strong wind gusts are possible with any thunderstorm that develops. The overall severe threat is quite low but it is definitely within the range of possibilities for a couple thunderstorms to turn severe on Wednesday afternoon, particularly when it comes to severe wind gusts.

On Thursday, the models are a little split on the potential. The NAM and RDPS are relatively more robust in SFC CAPE. Whereas the GFS and HRRR seem a little less convinced. The main uncertainty is how a potential shortwave might behave as it dips down out of Alberta. Currently both the GFS and Euro have it missing us whereas the NAM has it clipping the northeastern portion of our CWA. The placement and track of this shortwave will be the main thing to watch as it will directly play into how the thunderstorm potential will play out. -thor

AVIATION

17/12Z TAF Period

An area of concentrated showers between KGTF and KLWT will slowly dissipate through 17/15Z. Northwesterly flow aloft will maintain periods of widely scattered showers and low VFR clouds for much of the forecast period, with shower activity being most widespread over north-central MT this afternoon and tonight. VFR conditions will generally prevail, but there will be some MVFR stratus and mountain obscuration over and near the central island ranges through around 17/16Z, mostly impacting KHLN and KLWT. Then ceilings may trend towards MVFR over the plains tonight, mostly after 18/06Z. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 71 47 72 46 / 30 30 30 0 CTB 67 44 67 43 / 30 50 30 0 HLN 74 48 78 48 / 10 20 0 0 BZN 74 44 79 45 / 10 10 0 0 WYS 73 34 75 38 / 0 0 0 0 DLN 76 42 79 46 / 0 0 0 0 HVR 69 44 70 43 / 30 20 60 10 LWT 66 41 67 41 / 20 20 50 0

TFX WATCHES/WARNINGS/ADVISORIES

None.