High Wind in Big Belt, Bridger and Castle Mountains, Montana

Quite a few sensors in this zone measured sustained winds of 40 mph or greater, averaged over at least an hour, or gusts of 58 mph or greater, including mesonet sensors MTBDC Bridger Canyon (MT DOT), MTBZH Bozeman Pass (MT DOT), and MTDPC Deep Creek Pass (MT DOT), as well as RAWS station TT838 Battle Ridge. The peak gust observed was 84 mph at Bozeman Pass along Interstate 90.

Robust low to mid level flow westerly flow associated with a potent shortwave and attendant cold fronts resulted in a prolonged period of high-end winds and gusts across the entire region Dec 17 into the 18th. Multiple gusts in excess of 90 mph were observed in populated areas, with a peak observed gust of 104 mph west of Bynum. Prolonged power outages were observed across the region, mostly due to trees being damaged/falling over completely. Additional societal impacts included extremely difficult to impossible travel conditions, which prompted a Civil Emergency Message for areas along the Rocky Mountain Front the afternoon of the 17th.