As a powerful Arctic cold front moves south from Canada, unleashing howling winds and causing a bomb cyclone to form in the Midwest, the Lower 48 are being hit by an unusually long stretch of extreme winter weather.

The big picture: The extreme weather affects the whole country. The National Weather Service’s map of warnings and watches looks like a colouring book for the end of the world.

Temperatures will continue to drop everywhere except in the Southwest because of the front and storm system. This is an unusually wide range that will mess up holiday travel plans through this weekend.
What it means: Anyone caught outside in the Arctic air, strong winds, and a bomb cyclone could die. This is causing chaos on the roads and in the air during the holiday travel rush.

Threat level

As of Thursday evening, about 325 million Americans were under winter weather warnings and advisories for heavy snow, cold weather, and other winter weather dangers. These warnings and advisories covered the Pacific Northwest, the Plains, and the South all the way to the Gulf Coast.

“The National Weather Service‘s Watch Warning graphic shows one of the largest areas of winter weather warnings and advisories ever,” the NWS said in a forecast discussion, calling the event “historic.”
President Biden was told about the winter storm by leaders from FEMA and the National Weather Service. Biden told reporters, “I urge everyone to pay attention to the local warnings.” “This isn’t like when you were a kid and had a snow day. This is important.”

List of Emergency Declarations

The governors of Georgia, North Carolina, Kentucky, and Wyoming have all declared emergencies because of the severe weather system.

Thursday, about 8,000 flights in the U.S. were cancelled and another 3,000 were delayed.
On Wednesday night, roads were closed all over Colorado, from the town of Ault to the Wyoming border. This was because Buckley Air Force Base, which is about 20 miles east of Denver, reported that the temperature dropped from 46°F to 7°F in an hour.

The NWS says that the temperature in Cheyenne, Wyoming, dropped from 43°F to 3°F in 30 minutes, which is a record.

What to watch

The NWS warned Thursday that the front and storm will have “widespread disruptive and possibly crippling effects across the central and eastern United States.”

“A dangerous and record-breaking cold air mass is at the front of the impressive weather pattern. It is following a strong arctic cold front that is moving south across the southern Plains today and east into the Ohio and Tennessee Valleys by tonight.”
A storm is getting stronger as it feeds on the energy from the jet stream and the difference between warmer air to the east and colder air to the west. It will get much stronger Thursday night and Friday as it moves through the Midwest and into Ontario, Canada.
This storm is already making a lot of wind, and winds of up to 45 mph are expected up to 1,000 miles away from the centre of the storm.

PowerOutage.us says that as of Friday morning, more than 800,000 people have already lost power, with most of those in New England and the Southeast.
People may still lose power Friday and Saturday because of the cold, especially in the Midwest, Ohio Valley, and Northeast, where trees and power lines have fallen.
Some of the worst weather will happen near the Great Lakes.
The NWS says that on Friday, winds of 70 mph are likely to cause a lake surge in Buffalo that could push water 4 feet above the shoreline. The city is also expecting blizzard conditions, with as much as 3 feet of snow expected.
The surge will be a “seiche” event, in which water moves from one side of the lake to the other, usually because of strong winds or different air pressures.

What does “bomb cyclone” mean?

Zoom in: The storm is likely to be a “bomb cyclone” because it is getting stronger quickly, which is called “bombogenesis.”

This happens when the pressure in the atmosphere drops by at least 24 millibars in 24 hours.
In general, the stronger the storm, the lower the pressure.
The Arctic blast’s unusual reach
Using numbers: This storm is very unusual because more than 300 million people in the Lower 48 states are under winter weather warnings, watches, and advisories for extreme cold, heavy snow, and other dangers.

At minus 70°F, the wind chill in eastern Wyoming has been the coldest so far during this event.
Wind chill warnings and watches cover more than 30 states, from the Canadian border to the Texas Gulf Coast. Some places may set records for the biggest drop in temperature in a short amount of time. Computer models show that a “flash freeze” could happen in more than one state.
Even though global warming is happening, it still gets very cold, although cold snaps are getting less severe and shorter in the U.S.

During this event, it’s not likely that many all-time records will be set, but Casper, Wyoming did set one at minus 42°F.
Most states east of the Rockies are warming up the fastest in the U.S. during winter, and cold spells are getting less severe and shorter.