textproduct: Great Falls

KEY MESSAGES

- Scattered showers and thunderstorms will continue through Tuesday.

- Drier and warmer Wednesday and Thursday.

- The next weather system arrives on Friday, with cool temperatures and a chance for mountain snow by Sunday.

DISCUSSION

/Issued 239 PM MDT Mon Sep 7 2026/

- Meteorological Overview: An upper level low will move eastward across the northern tier of MT tonight. This will allow for scattered showers and thunderstorms to continue over the CWA, with an area of steady rainfall continuing around Glacier Park and in the Cut Bank area. On Tuesday, a 2nd upper level trof quickly moves eastward across the southern half of the state, resulting in scattered showers/thunderstorms over Southwest MT on Tue afternoon.

By Wednesday, the flow aloft becomes more zonal resulting in warmer air slowly moving back into the CWA. The zonal flow will not last long, as the next upper level low begins to approach the CWA by late on Friday. This upper level low moves over Central MT by Sunday. With cool temperatures, snow levels on Sunday will lower to around 7000 feet or so. Some snow accumulations are looking likely, especially in Glacier Park. This system will begin to exit the CWA on Monday.

- Forecast Confidence & Scenarios: The continues to be a chance for flooding around Glacier Park, as periods of rain continue into Tuesday.

Otherwise, the main concern this weekend will be how low does the snow level get. Currently we are thinking snow levels could be as low as 7000 feet by Sunday morning. Current thinking is snow accumulations of 3 to 6 are possible at the highest elevations.

AVIATION

08/00Z TAF Period

A rain shield north of KGTF will continue along US Highway 2 and the northern Rocky Mountain Front throughout this TAF period, bringing rain showers to KCTB and KHVR. The rain showers could be moderate at times. Rain showers will impact KGTF later in the TAF period, around 17Z. Mountain obscuration and reduced visbilities will occur as a result of the rain showers. Breezy winds will decrease after sunset this evening for KBZN, KEKS, KWYS and KHLN, before picking back up around midday tomorrow. For KGTF, KCTB, KHVR and KLWT, while the winds will decrease slighty after sunset, they will remain gusty with a westerly component throughout the TAF period.

For KGTF: While the rain shield generally looks to stay north of the terminal this evening, there is a chance that a light shower could form just south enough to produce a light rain over the terminal. There is more confidence in rain showers forming over the terminal around 17Z. The breezy southwesterly wind will begin to decrease late this evening, but only slightly, as gusts around 25 KT are still expected throughout the TAF period. The wind will become predominately westerly around 17Z. Due to the gusty winds from 240-270 degrees, there is high confidence that the cross-wind threshold will be exceeded during this TAF period. -Dzomba

HYDROLOGY

An areal flood watch will continue for the east side of Glacier Park, Browning, Cut Bank and Shelby areas into Tuesday. Periods of steady rain continue to affect this area, with most locations receiving between 2 and 3 inches of rainfall already in this area. An additional inch of rainfall is possible between now and Tuesday. Thus some minor flood impacts could develop later today or into Tuesday morning. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 48 63 43 77 / 40 70 10 0 CTB 44 61 44 70 / 90 70 0 0 HLN 43 67 42 78 / 0 20 0 0 BZN 39 69 38 79 / 0 20 10 0 WYS 30 64 30 70 / 0 0 0 0 DLN 36 70 37 78 / 0 0 0 0 HVR 46 64 43 76 / 90 90 40 0 LWT 45 64 41 76 / 10 40 20 0

TFX WATCHES/WARNINGS/ADVISORIES

Flood Watch through Tuesday morning for East Glacier Park Region- Eastern Glacier, Western Toole, and Central Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Northern High Plains-Southern High Plains-Southern Rocky Mountain Front.