Thunderstorm Wind in Beaverhead County, Montana

Ambient station Chicken Coop measured a severe gust.

Robust troughing moving inland across the Pacific NW began to usher cooler air southward on the 19th into the 20th across northern areas. In the meantime, deep mixing and weak shear with marginal instability managed to produce isolated severe gusts across SW MT on the 19th. Heading into the 20th the instability decreased, but southerly to southwesterly flow increased aloft over SW MT. This resulted in a period of strong winds and gusts, strongest in the Madison River Valley. As the Pacific troughing moved further inland, attention then turned to precipitation, which fell in the mountains as snow Saturday into Sunday (June 20-22). All the while, strong winds/gusts were occurring across portions of the Hi-Line as the cooler air surged southward.