Scientists Warn 'Bomb Cyclone' Brings Strong Winds, Cold Temperatures

The Eastern United States is being hit by a really powerful winter storm that scientists are calling a bomb cyclone. And yes, that is a scientific term.

The National Weather Service forecasts that the storm, which has struck Florida and the Carolinas, will move northward along the Eastern Seaboard on Thursday and Friday. It will bring snow, ice, strong winds, massive storm surges and plummeting temperatures all the way up to Maine.

Here is what created this monster winter storm.

First, the jet stream brought cold, dry air from Canada southward this past week, casting an unusually cold spell on the entire Eastern United States. That mass of cold air eventually collided with relatively warm, moist air off the Southeastern coast, giving birth to this winter storm.

"Very warm air coming next to cold air mass creates a lot of energy," says Jeffrey B. Halverson, a climatologist at the University of Maryland, Baltimore County.

It also creates a dramatic decline in air pressure, he says. "The pressure is going to drop very, very rapidly."

That's where the word "bomb" comes in, says Jeff Weber, a climatologist at the University Corporation for Atmospheric Research. "We call storms that drop 24 millibars in 24 hours a bomb, a bombogenesis, the beginning of a cyclone."

The more technical (and less eye-catching) term is a baroclinic midlatitude cyclone. This particular one has similarities to Superstorm Sandy, which hit the Eastern United States in 2012.

Unlike this winter storm, Sandy began as a full-fledged hurricane. "As it moved north, it interacted with cold air and transitioned into a baroclinic midlatitude cyclone," Weber says. "And that happened literally as the eye was getting ready to make landfall."

Sandy was more powerful than this new storm, because it had more time to build up energy as it moved north from the Caribbean, he says.

Nevertheless, this storm is expected to be very powerful. Scientists are forecasting that the air pressure in the storm will drop by "about 50 millibars over the next 24 hours," says Weber. "So this will be a big deepening and strong intensification of the storm over the next 24 hours."

"This storm is a big, big wind-making machine," says Halverson. "This is going to cause a lot of problems."

The National Weather Service predicts between 6 and 12 inches of snowfall between Virginia Beach and Boston. Northern New England could get more than 12-18 inches. Eastern Long Island and northern New England are likely to see blizzard conditions.

There will also be coastal flooding and storm surges that can destroy coastal properties and cause beach erosion, especially up along the New England coastline, says Halverson.

Massachusetts and Maine are likely to see widespread power outages caused by gusty winds.

But the storm's impacts won't end there.

"This storm is going to pull down a huge amount of arctic air," says Halverson. "On Friday and Saturday, temperatures are going to be in the gutter."

Temperatures could drop down to single digits, or even below zero. "And if you're going to be out of power, you're really going to be in trouble."

States such as Massachusetts and Maine should prepare shelters for people, he says. "Sheltering for warmth is going to be key, for potentially several days."

Copyright 2018 NPR. To see more, visit http://www.npr.org/.