'Dangerous winds' to hit Montana Wednesday, weather service warns of serious damage

No corner of Montana will be spared from the effects of an incoming "dangerous" weather event on Wednesday.

"This isn't something that's to be taken lightly," said James Brusda, lead meteorologist at the Great Falls National Weather Service office. "Your safety is going to be of our concern tomorrow."

The National Weather Service is warning of "damaging winds" resulting from the very strong low pressure system coming down from the Canadian Rockies.

"A cold front sweeps across the region Wednesday morning into early afternoon, introducing persistent, high-end winds and gusts across the region through the evening and early overnight," a weather service bulletin reads.

A stronger and more widespread high-wind event is expected with the potential for gusts up to 80 mph for most of the region and up to 100 mph along the Rocky Mountain Front, NWS officials said.

"We are expecting that there's going to be the high propensity for some trees to blow over in this wind event," said Brian Conlan, meteorologist with the National Weather Service office in Missoula.

A potential for snow squalls is forecast with the passage of the cold front. Snow squalls, often associated with strong cold fronts, move in and out quickly, and typically last less than an hour. The sudden whiteout conditions combined with falling temperatures produce icy roads in just a few minutes.

The weather service is projecting "high confidence" in the wind event forecast, but "moderate confidence" in the snowfall component, so some adjustments in timing and magnitude of the weather impacts are expected as the event approaches, the NWS said.

All four of the state's National Weather Service offices convened a public briefing Tuesday alerting the public about the forecast.

"It is worth emphasizing again that the combination of the magnitude of these high-winds, as well as the duration of the high-end winds will combine to pose impacts to infrastructure," a weather service bulletin reads.

The wind

The entire state of Montana is under a high-wind warning, with varying levels of intensity.

"Our cities are used to wind east of the divide, but wind speeds 85 miles per hour, those are rare, and those will cause problems," Brusda said.

All of Montana's major cities will see west winds 30-40 mph with gusts up to 70 mph.

The Rocky Mountain Front, places like East Glacier and Browning, will get hit the hardest. Forecasters are calling for west winds with gusts up to 90 mph developing Tuesday night along and west of U.S. Highway 89, with gusts up to 80 mph east of the highway.

Mountain ranges, passes and some valley bottoms will see west winds 30-45 mph with gusts up to 80 mph.

The high-wind warnings are in effect from 3 a.m. Wednesday to midnight.

"We want to stress is that this is going to occur over all north-central and southwest Montana, and it's going to be a long duration," Brusda said.

The snow

Precipitation will also accompany the weather system but will remain isolated to mountainous areas in western part of the state.

For the Continental Divide along the Rocky Mountain Front, heavy snow is expected. Total snow accumulations between 4 and 10 inches are expected at Marias Pass with higher amounts over the mountains in Glacier National Park.

For Marias Pass west to Polebridge and south to Swan Lake, heavy snow is also expected, with total accumulations of 2-5 in inches in the valleys and 8-12 inches at pass level.

"Most of the precipitation in our area is going to fall prior to this cold front tomorrow, between 6 and 9 a.m.," Conlan said. "What we're looking at is about 1 to 3 inches of liquid precipitation in the mountains."

The winter storm warnings are in effect from 8 p.m. Tuesday to 11 p.m. Wednesday.

How to prepare for the wind 

High winds may move loose debris, damage property and cause power outages.

"This will be damaging wind that will impact your property and for anyone traveling, especially north south facing roads, those crosswinds will be have a high risk of blowing over, especially those high-profile vehicles," said Nicholas Vertz, meteorologist with NWS Billings. "Travel could be difficult, especially for high-profile vehicles. Damaging winds will blow down trees and power lines, so power outages are expected. Travel will be very difficult, especially for high-profile vehicles.

People are urged to secure loose objects that could be blown around or be damaged by the wind.

If possible, consider delaying travel during the period of highest winds or finding an alternate route.

How to prepare for the snow

Travel could be very difficult to dangerous and tire chains may be required for some vehicles. Visibility may drop below a quarter-mile at times due to falling and blowing snow.

Those in the backcountry should ensure they are prepared for dangerous conditions.

If you must travel, keep an extra flashlight, food and water in your vehicle in case of an emergency, the NWS said. The latest road conditions can be obtained by calling 511 or visiting the Montana Department of Transportation Road Report website.