High Wind in Gates of the Mountains, Montana

Mesonet sensor MTSBN Sieben Flats (MT DOT) measured multiple gusts in excess of 60 mph, including a peak gust of 71 mph. The site also measured high sustained winds averaging 48 mph between 4 and 5 PM. Additionally, a trained spotter 7 E of Maryville reported a peak gust of 68 mph.

A robust trough digging southeastward from the Pacific Northwest brought a belt of strong mid and low-level westerly flow across the majority of the region December 18. Given the favorable timing of the strongest flow and cold front, winds were easily able to mix to the surface. A respectable pressure gradient also developed across the area, which helped a few sites reach high sustained winds. In northeastern areas the wind took longer to develop, eventually needing the surface low to pull away from AB toward SK. This propelled a front through the area that brought both strong winds as well as rain that fell onto very cold surfaces, resulting in slick roads.