Blizzard Slams Helena Valley, Closing I-15 and Highways Across Central Montana

Zero visibility and multiple vehicle crashes forced the closure of Interstate 15 in both directions between Lincoln Road and Wolf Creek by 3 p.m. Saturday, March 14, as a late-season blizzard drove whiteout conditions across the Helena Valley and deep into central Montana.

Lewis and Clark County Sheriff Leo Dutton, coordinating with the Montana Department of Transportation, issued a sweeping travel declaration covering the entire stretch from Helena north to the Canadian border. "Together with the Montana Department of Transportation, we are declaring severe driving conditions from the Lewis and Clark County line at Helena North to the Canadian border. Travel is not recommended. Severe conditions exist," Dutton said.

U.S. Highway 287 between Augusta and Choteau was also closed. Road camera footage from Sieben Flats on March 14 captured what conditions looked like in real time: emergency response vehicles moving through near-total whiteout, the image later described simply as "Sieben whiteout."

The National Weather Service in Great Falls issued a blizzard warning for Teton County, Pondera County, and parts of both Cascade and Lewis and Clark Counties, citing additional snow accumulations of 2 to 6 inches and wind gusts as high as 40 mph. A winter storm warning covered nearly all of central Montana through 6 p.m. Saturday. KTVH reported the two-day snow totals from Friday and Saturday were shaping up to be the most significant of the entire winter for north-central Montana and Helena, with as much as 18 inches forecast for lower elevations in north-central Montana. The Great Falls area was projected to see up to a foot.

Helena Valley's trajectory through the storm was more complicated. Daybreak Weather's Friday morning forecast noted that Helena was sitting on the warmer edge of the system, with a rain and snow mix turning to mostly rain by afternoon and a high in the low 40s. The conversion back to snow came later, when the cold front pushed through overnight. Valley totals were projected at 3 to 6 inches, with considerably higher amounts in the surrounding mountains. Great Divide reported up to a foot of new snow from Friday's precipitation alone.

Lewis and Clark County Emergency Management warned residents through a Facebook post that conditions had already caused infrastructure damage. "If you don't have to be on the roads, don't go. Snowfall combined with strong winds are causing downed trees and power lines," the post read. "Snow is drifting on some roadways, especially in the West and North of the county."

County Public Works stretched its resources across the road network, though the post acknowledged limits: "Our Public Works has deployed everything they've got out on the roads to keep main routes open. There will be some roads they can't get to for a while and some that will drift again before they can get back to them."

Dutton said crews were repositioning further north, where conditions were even more severe, and warned that additional closures were likely, including Stemple Pass. "We are advising people to stay off the roads if they don't need to be out," he said.

KTVH flagged mountain passes as the area of greatest concern, noting that feet of snow would fall at higher elevations and that even some lower-elevation roads would be dangerous at times.