The National Weather Service office in Great Falls has issued a High Wind Warning covering the Rocky Mountain Front, MacDonald Pass, and the Upper Blackfoot corridor, with a separate High Wind Watch in effect for the Helena Valley — and residents should expect conditions to deteriorate Wednesday evening and persist well into Thursday.

Under the Warning, westerly winds of 40 to 50 mph are forecast along the Rocky Mountain Front and adjacent foothills and plains, with gusts potentially reaching 90 mph in the most exposed areas. The Warning is in effect from 6 p.m. Wednesday through midnight Thursday night and covers Eastern Glacier, Western Toole, and Central Pondera Counties in addition to the Front itself. The Helena Valley Watch, which runs from late Wednesday night through Thursday afternoon, calls for sustained winds of 30 to 40 mph with gusts up to 60 mph.

The NWS is warning that high winds may move loose debris, cause property damage, and produce isolated power outages across the region. Drivers of high-profile vehicles — semis, campers, trailers — are specifically cautioned that travel could become dangerous, particularly on exposed stretches of Interstate 15 and U.S. Highway 12 near MacDonald Pass. Helena residents should secure any outdoor furniture, yard materials, or unsecured structures before Wednesday evening.

Residents are encouraged to monitor the latest NWS Great Falls forecasts for updates, as warning boundaries and timing may shift as the system moves through.