US Braces For "Bomb Cyclone" Storms - But What Is It?

It's as explosive as it sounds.


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer

Four people out in a snow storm

Pictured: a bad idea. Image credit: justoomm/Shutterstock

As Bing Crosby once crooned, “I’m Dreamin’ of a White Christmas.” But that dream may become something of a nightmare this year for more than 200 million Americans, as extreme Arctic storms now make their way across the central and eastern parts of the country.

US residents in nearly every state are currently living under various weather alerts, with blizzard conditions expected in the Great Lakes region and flash freezing expected across the east coast. Even Florida and areas on the Mexican border are facing warnings of dangerous weather, including winds of up to 60 miles (100 kilometers) per hour. 


“Temperatures 40 degrees [22 degrees Celsius] below average and dangerous life-threatening wind chills as low as 50 degrees below zero [-46C] are possible in the northern Rockies and northern Plains,” warned the National Oceanic and Atmospheric Administration (NOAA) Wednesday. “Sub-zero to single-digit temperatures are likely across the central Plains, Midwest, Great Lakes, Ohio Valley and Midsouth.”

But it’s not just the cold weather that’s the problem. Meteorologists are warning of a “bomb cyclone” hitting the country – an explosive name for an equally devastating phenomenon.

“More correctly, it should be called explosive cyclogenesis, which is when the central pressure of a low pressure system falls dramatically – by 24 millibars in 24 hours,” explained Kirsty McCabe, a weather presenter for the UK’s Sky News.

“These intense storms bring heavy precipitation and very strong winds,” she said. “In the US right now, very cold Arctic air is being pulled in, with the freezing weather causing further complications.”


Bomb cyclones form thanks to the interactions between powerful jet streams of warm and cold air, she explained. As the two temperatures clash, the atmospheric pressure plunges rapidly, as does the temperature – on Wednesday, in Dillon, Montana, the temperature fell 26 degrees Fahrenheit (14.5C) in just three minutes, the National Weather Service (NWS) reported.

“This is not like a snow day, when you were a kid,” President Biden warned on Thursday. “This is serious stuff.”

Meanwhile, Colorado saw temperatures plummet from 42F (5.5C) to -9F (-22.7C) on Thursday, and in Cheyenne, Wyoming, the thermometers dropped from 43F (6C) to 3F (-16C) in just half an hour. By Friday, the NWS was reporting temperatures in places across the US that were more than 30F (16.5C) colder than the day before.

The National Weather Service advised similar or worse conditions over the coming weekend, with temperatures of -50F to -70F being a real possibility in some parts of the US. Even in cities and metropolitan areas, the agency warned, frostbite could become a significant danger.


As millions of Americans make plans to visit friends and family over the holiday season, the bomb cyclone is “a unique and dangerous situation”, Ohio governor Mike DeWine said Thursday. Nearly 6,000 flights in the US have already been canceled for Thursday and Friday, according to the flight-tracking site FlightAware, and in Canada, WestJet alone has canceled more than 250 flights due to depart Friday.

Even at ground level, traveling is going to be very perilous – so it’s best to avoid it at all costs, cautioned the NWS on Thursday. “Dangerous wind chills will create a potentially life-threatening hazard for travelers that become stranded,” they advised. “If you must travel, prepare for extreme cold. In some areas, being outdoors could lead to frostbite in minutes.”

“Today is the first day of astronomical winter,” they warned. “And it will certainly feel like it for much of the nation through the end of this week.”

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