At least 180,000 remained in the dark early Thursday in the states of Washington, Oregon, Idaho and Montana, according to PowerOutage.us, a number likely to grow when the strong gusts of wind extended eastward.
Several gusts above 107 km / h were measured in Alta, Utah, a mountain town southeast of Salt Lake City in the Wasatch Range. Mount Sentinel in Montana gusted to 125 mph. But perhaps the most notable measurement came from Laramie, Wyo. – a flat area removed from all mountains ̵
A litany of scattered to widespread gusts between 80 and 95 mph buffeted Wyoming and Montana. Gusts in Billings, Mont., Hit 69 mph, as they did in Bozeman, while Great Falls saw a gust of 76 mph and Helena a gust of 80 mph. A number of locations in Montana reported record wind speeds in January.
“Normally you can count on the Rocky Mountain Front to always have the strongest winds in our area,” said Christian Cassell, a meteorologist from the National Weather Service at the Great Falls office. “This was a bit more of an unusual storm. The wind effects were a little more widespread. ”
He said the strongest winds began Wednesday morning after a warm front slipped through, with sunshine warming the air enough to rise and penetrate into strong winds associated with a low-jet jet stream. This flow of fast-moving air about 10,000 feet above the ground provided momentum that was drawn all the way down to the surface.
“We basically brought the jet stream down to the surface in a lot of Montana,” Cassell said.
A key factor was also a significant air pressure gradient or change in air pressure with distance. A strong high-pressure system to the west over Idaho and the Columbia River Basin squared with a weak low over southern Manitoba. As air moves from high pressure to low pressure, it slid rapidly eastward and increased in velocity as it jumped through the northern United States and took over a northern component due to the strength of Coriolis.
The strength of the wind is proportional to how steep the change in air pressure with distance is. It’s like a sled – you zipper downhill faster when the hill is on a steeper slope.
The system shifted east late Wednesday, bringing gusts of 65 to 80 km / h to western parts of Dakota and Nebraska.
Glasgow later saw a gust of 79 mph, only 3 mph cloudy by the record set during a series of powerful thunderstorms on July 3, 2000. However, the difference between a severe thunderstorm and this storm was the duration of strong winds. Thunderstorms tend to bring short periods of strong winds, whereas this storm stormed several hours.
“Last February, we had a pretty remarkable windstorm over central Montana,” Cassell said. “In Great Falls, it felt like the damage to one was a little more significant … but [it] was a little more localized to central Montana. This one was just so prevalent. It went into Canada, all over Montana and even south into Wyoming. ”
In Saskatchewan, vehicles were stranded, with strong winds overlapping with snowfall. Blizzard warnings were issued by Environment Canada for much of Saskatchewan and Manitoba along with freezing rain warnings for parts of Manitoba.
Elsewhere, a 99 gust was measured at Glen Haven, Colo., About 15 miles southwest of Fort Collins, while Crisman, just five miles west-northwest of Boulder, plunged up to 94 mph. Breckenridge, a popular ski destination, reported a gust of wind of 106 km / h.
Truckers were urged to stay off I-76 in Colorado while I-80 was closed for a period between Cheyenne and Rawlins, Wyo. Cheyenne, located in a flat area, reported a gust of 89 km / h shortly after noon.
Meanwhile, the same storm system behind the wind releases blizzard conditions in parts of the corn belt, northern plains and the Upper Midwest. A snowstorm warning is in fact east of the James Valley in South Dakota, including Watertown and Sioux Falls, as well as in most of western Iowa and southwestern Minnesota. Des Moines and Sioux City are both included in the snowstorm warning, while Minneapolis is covered by a winter weather guide.
After some initial light snow showers, the biggest snowfall is expected to happen late Thursday night to Friday morning. A wide 3 to 5 inches will cover most of Iowa, Minnesota, Wisconsin and western parts of Michigan’s Upper Peninsula. Amounts that top half a foot and flirt locally with 10 inches are possible in northern Iowa and southeastern Minnesota.
The storm system, which also brought unique rainfall to Oregon and Washington after directing an atmospheric river into the northwest Pacific, will push all the way to the east coast Friday night. Parts of the east coast expect showers along the cold front to start the holiday weekend, but fortunately the wind in this storm system will have abated before then.