High Wind in Cascade County Below 5000ft, Montana

ASOS station KGTF Great Falls Airport measured a peak gust of 71 mph. The ASOS also measured sustained winds, averaged over more than an hour, of 45 mph. Additional sensors in the zone to measure gusts of or greater than 58 mph include FW5493 Vaughn (58 mph), FW1843 Great Falls (61 mph), AWOS station K1AM Alpha (60 mph), and MTM76 Cascade E MDA (61 mph). Montana mesonet site Sun River SE (acesunri) measured a 63 mph gust as well as high sustained winds of 41 mph, averaged over three hours (Noon to 3 PM). Finally, a social media post from broadcast media showed several downed trees in Great Falls as a result of the wind. At least one roof was damaged based on available photos.

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.