textproduct: Great Falls

KEY MESSAGES

- Warm, breezy, and generally dry through the rest of the afternoon.

- Daily chances for showers and thunderstorms Sunday through Wednesday; a few may be strong to severe.

DISCUSSION

/Issued 529 PM MDT Sat Jul 4 2026/

- Meteorological Overview:

Breezy conditions will continue through the rest of the day before tapering off towards the evening hours. A couple isolated showers may try to form but nothing significant or impactful is expected at least through the rest of Saturday.

Heading towards Sunday, a shortwave trough moving across the region along with a shift to more southwesterly flow in Montana will allow for more moisture and instability across the region through the evening hours. Hi-res model guidance has the highest shear across the northern half of our CWA but has the higher CAPE values mismatched towards the southern portion of the CWA. Overall the result of this setup will be a chance for showers and thunderstorms across a good portion of the region but a higher chance for strong to severe thunderstorms towards the middle section of our CWA. The main threats with these thunderstorms will be hail, strong wind, and heavy downpours.

For Monday and Tuesday, a shortwave trough riding along southwesterly flow will bring ample moisture and instability to the region allowing for showers and thunderstorms, especially across Southwest Montana. The main threats will be hail, strong winds, and heavy downpours. Model soundings indicate that precipitable water values are going to be close to or potentially above the daily climatological max. With this in mind, there will some concerns for localized flooding, especially in urban and poor-drainage areas and along burn scars with temporary rises in creeks and streams possible.

Behind the trough some temporary shortwave ridging will build allowing for temperatures to warm Tuesday into Wednesday across the region. By Wednesday a Pacific trough starts to make its way into the region bringing a chance for thunderstorms primarily across the northern half of the CWA and a chance for severe weather, especially east of a line between Chester and Great Falls. The level of confidence in thunderstorms on Wednesday afternoon remains similar to the previous forecast. With surface temperatures across North-Central and Central Montana expected to be in the upper 80s to low 90s and dewpoint temperatures expected to be in the upper 50s to low 60s, that alone is usually enough to cause some level of concern. The addition of the cold front is then expected to provide the forcing needed to kick-start thunderstorm activity across the northern half of the CWA.

The GFS continues to put out a more mellow version of events across the region while the Euro has been more robust in the coverage and intensity of thunderstorms. The Canadian has been a little more selective in the coverage area compared to the Euro but still suggests strong storms are possible over the eastern half of the state. The two main things that introduce the highest amount of uncertainty are the track and timing of the Pacific trough. This is where the GFS, Euro, and Canadian all start to diverge. Whether the trough ends up further south or north or what time of day the cold front ends up arriving in our portion of the state will all make huge differences in how the potential for severe weather pans out. Ultimately it is still too early to have a clear grasp on the finer details but it is something that will be watched carefully in future forecasts. In the meantime, folks should be prepared for the potential of strong to severe thunderstorms on Wednesday afternoon, especially north of the Highway 200 corridor. -thor

AVIATION

05/06Z TAF Period

The main concern this TAF period will be for afternoon and evening showers and thunderstorms across portions of Southwest through Central Montana Sunday. Gusty winds, hail, and lightning will all be a concern with thunderstorms that form. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 55 85 54 77 / 0 0 10 20 CTB 49 80 48 74 / 0 0 0 0 HLN 56 87 57 79 / 0 20 20 20 BZN 54 88 54 83 / 0 40 40 20 WYS 44 84 48 82 / 0 20 20 20 DLN 52 86 53 80 / 0 30 20 40 HVR 56 86 53 81 / 0 0 10 0 LWT 53 84 51 77 / 0 20 60 10

TFX WATCHES/WARNINGS/ADVISORIES

None.