The National Weather Service office in Great Falls issued a Dense Fog Advisory early Monday, October 26, effective from 12:42 a.m. through noon MDT, covering a broad stretch of southwest and central Montana including areas familiar to Helena-area commuters and recreationists.
The advisory covered the Canyon Ferry Area, the Elkhorn and Boulder Mountains, the Beaverhead and western Madison counties below 6,000 feet, the Gallatin Valley, Gallatin and Madison County Mountains, the Centennial Mountains, the Madison River Valley, the Missouri Headwaters, and northwest Beaverhead County. Visibility in affected areas was forecast at one quarter mile or less.
The NWS warned that low visibility could make driving dangerous and urged motorists to slow down and use low-beam headlights in foggy conditions. Canyon Ferry Road and the highway corridors connecting Helena to the Boulder Valley were among the areas where residents needed to exercise particular caution during the morning commute.