textproduct: Great Falls

KEY MESSAGES

- Thunderstorms with severe wind gusts in excess of 60 mph possible on Wednesday, especially across the plains. - Winds will be gusty across Southwestern Montana Wednesday and Thursday, bringing elevated to critical fire weather conditions. - Temperatures near to slightly below average expected this week.

DISCUSSION

/Issued 250 PM MDT Tue Sep 1 2026/

Southwesterly flow on the west side of a quick moving upper level ridge has begun to bring increasing moisture and warmth to Southwestern and North Central Montana. Most lower elevations locales have reached the upper 70s/low 80s, which is just slightly warmer than our average highs for this time of year. In addition to the warmth, a few showers and thunderstorms have begun to pop up across Beaverhead County, and these will gradually drift to the north/northeast through the remainder of the evening. While severe wind gusts are not expected, a few gusts to around 50 mph will be possible with some of the stronger storms.

Winds increase on Wednesday as a shortwave trough embedded in the flow moves overhead. Winds will be strongest across Southwestern Montana, particularly during the late morning and afternoon, especially in the north/south oriented valleys. As this shortwave progresses further north, showers and thunderstorms will develop and move northward towards the plains. As these storms reach the plains, the combination of strong winds aloft, along with dry mid levels and a very deep and well mixed boundary layer, some of the storms will begin to produce strong wind gusts, some of which will likely be over 60 mph. With this in mind, SPC has upgraded our Marginal risk to a Slight risk (1/5 to 2/5) for tomorrow afternoon.

Winds will continue across Southwestern Montana as an upper level jet streak moves overhead, but winds are likely not going to be quite as strong as Wednesday. Thursday should also bring generally drier conditions to the Treasure State East of the Divide, aside from a few isolated stray showers. Looking ahead to the weekend, an upper level low situated just off the coast of Oregon and Washington will keep us on the unsettled side, and may eventually allow some moisture from what is currently Tropical Storm Marie to work its way through the Western US and into Montana early next week. Ludwig

AVIATION

02/00Z TAF Period

High confidence VFR conditions dominate most of the period across all terminals. A weak passing disturbance will bring isolated to scattered light showers between 02z and 08z. Confidence in direct terminal impacts remains low, so utilized Prob30 groups to handle the threat. KWYS, KBZN, and KHLN are expected to remain VFR even within any light activity. However, lower cloud decks across southwest Montana may support brief periods of MVFR at KEKS. As we move through the night winds largely calm down before ramping up around 20z Wednesday afternoon. Widespread winds of 20-30kt are expected with southwest Terminals KWYS and KEKS seeing gusts pushing 35kts with a southwest direction. Occasional smoke from regional wildfires will continue to pose occasional reduction in slantwise visibilities across all terminals.

For KGTF: Winds will continue to be light and variable through at least 05z with chances of exceeding the 15kt crosswind threshold near 20% as winds are largely out of the southeast. Winds begin to increase after 05z as wind direction flips to a southwesterly direction making the probability of crosswinds exceeding the stated threshold lowered to near 10%. -JR

PRELIMINARY POINT TEMPS/POPS

GTF 85 57 85 50 / 0 0 40 10 CTB 83 52 80 46 / 0 0 80 50 HLN 86 52 82 48 / 0 40 40 10 BZN 82 50 81 48 / 10 30 10 0 WYS 69 38 66 34 / 60 70 20 0 DLN 81 46 77 44 / 0 50 20 0 HVR 88 54 90 50 / 0 0 30 40 LWT 83 55 85 49 / 0 0 10 10

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Warning from noon to 9 PM MDT Wednesday for Madison River Valley.

High Wind Watch from Wednesday evening through Thursday evening for Madison River Valley.