The National Weather Service office in Great Falls issued a Winter Weather Advisory Thursday morning for the mountain areas around Helena, with snow and gusty winds expected through midnight Friday. The advisory covers MacDonald Pass, the Upper Blackfoot drainage, the Big Belt, Bridger, and Castle Mountains, and the Ruby and Southern Beaverhead ranges.
Forecasters are calling for two to five inches of total snow accumulation with wind gusts reaching up to 35 miles per hour. The advisory period runs from noon Thursday through midnight, timed squarely over the Friday evening commute window — which the NWS explicitly flagged as an impact zone.
For Helena drivers, MacDonald Pass on U.S. Highway 12 is the most immediate concern. The pass sits at over 6,300 feet and can deteriorate quickly when a system moves through. The Montana Department of Transportation's 511 system provides real-time road condition updates for the pass and surrounding routes.
Residents heading into the hills for the weekend should check conditions before departure. The advisory does not cover the Helena Valley floor, but mountain roads feeding recreation areas and ranch properties in the affected ranges will likely see accumulating snow and reduced traction.