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A “bomb cyclone” is bringing hurricane-force winds and blizzard to the Great Plains

It’s highly unusual for the Plains to experience such a windy winter storm. 

A satellite image of water vapor over the Rockies and Great Plains on Wednesday.

A historic “bomb cyclone” storm is bringing strong winds, heavy snow, and rain Wednesday and Thursday to the central United States — from Minnesota all the way to Texas. The National Weather Service says severe blizzard conditions are expected in some areas, as well as isolated flooding. (Read the NWS’s latest forecast discussion here.)

What’s unusual about this winter storm is its very intense winds, which are expected to reach up to 80 mph in some places. As meteorologist Ryan Maue noted on Twitter, “While not a tropical system, winds will rival what’s seen in a Category 1 hurricane.”

The mid-Mississippi Valley could get tornadoes, while Kansas and Nebraska could see severe hail, the NWS’s Storm Prediction Center said. Between 1 and 2 feet of snow could fall in some areas of Colorado, Wyoming, Montana, Nebraska, and the Dakotas.

But what exactly is a bomb cyclone? As Vox’s Jen Kirby explained, it is when a weather system drops pressure very, very quickly.

When pressure drops, storms intensify and spin counterclockwise (a.k.a. form a cyclone). In this case, the pressure is due, in part, to the strong differences in temperature between a warm subtropical air mass and a cold Arctic one to the north.

“When you have this really tight temperature gradient, you can get these pieces of energy — weather disturbances — coming through the atmosphere,” meteorologist Ed Vallee explained to Kirby. (Check out their interview for a great explanation of the January 2018 bomb cyclone.)

It’s extremely rare for the Plains region to experience a bomb cyclone, as the Denver Post notes. “It takes an unusually large air temperature difference over land for such a disturbance to take place,” WeatherNation TV’s Chris Bianchi told the paper this week. And this one is so low-pressure, it’s already breaking records in Colorado, according to the NWS.

To see the storm’s origin in the Southwest and subsequent evolution, check out this brief thread from atmospheric scientist Philippe Papin:

Remember: winter weather is very dangerous!

It’s important to stress: Winter weather is very, very dangerous. Cold temperatures and high winds are a recipe for frostbite and hypothermia. Hospitals routinely see an uptick in admissions for cold-related symptoms and heart problems in the days after a snowstorm. And then there’s traffic: About 800 people die in cold weather-related traffic accidents every year.

The National Weather Service is advising residents of Denver and Boulder to cancel all travel plans on Wednesday. “Blizzard conditions are expected from the Front Range across the central and northern Plains,” it said. “Travel will be dangerous, if not impossible.”

So as we wrap up these final days of winter, stay warm, stay off the roads when they’re icy, and stay safe.

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