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What the heck is a ‘bomb cyclone’ anyway? 

  • Finley Bork, 7, uses a boogie board, typically used on the beach, for sledding down a hill on a golf course at the Isle of Palms, S.C., Wednesday, Jan. 3, 2018. A brutal winter storm smacked the coastal Southeast with a rare blast of snow and ice Wednesday, hitting parts of Florida, Georgia and South Carolina with their heaviest snowfall in nearly three decades. (AP Photo/Mic Smith) Mic Smith

  • Children sled down a hill on a golf course at the Isle of Palms, S.C., Wednesday, Jan. 3, 2018. A brutal winter storm dumped snow in Tallahassee, Florida, on Wednesday for the first time in nearly three decades before slogging up the Atlantic coast and smacking Southern cities such as Savannah and Charleston, South Carolina, with a rare blast of snow and ice. (AP Photo/Mic Smith) Mic Smith Photography LLC

  • Sid Rismani skis behind a car on Waterway Blvd. while heavy snow comes down on the Isle of Palms, S.C., Wednesday, Jan. 3, 2018. A brutal winter storm dumped snow in Tallahassee, Florida, on Wednesday for the first time in nearly three decades before slogging up the Atlantic coast and smacking Southern cities such as Savannah and Charleston, South Carolina, with a rare blast of snow and ice. (AP Photo/Mic Smith) Mic Smith Photography LLC

  • Jason Thorton with Coastal Seafood and Propane in Leland N.C. fills up another propane tank, Wednesday, Jan. 3, 2018 as a line of cars waits for their turn. Thorton has been filling tanks since 8 am in response to the coming winter storm moving up the East Coast. (Ken Blevins/The Star-News via AP) Ken Blevins

  • A person walks in the snow on King Street in Charleston, S.C., Wednesday, Jan. 3, 2018. A brutal winter storm smacked the coastal Southeast with a rare blast of snow and ice Wednesday, hitting parts of Florida, Georgia and South Carolina with their heaviest snowfall in nearly three decades. (Matthew Fortner/The Post And Courier via AP) Matthew Fortner

  • Vehicles move along a snow and ice covered Interstate 26, near Savannah, Ga., Wednesday, Jan. 3, 2018. A brutal winter storm dumped snow in Tallahassee, Fla., on Wednesday for the first time in nearly three decades before slogging up the Atlantic coast and smacking Southern cities such as Savannah and Charleston, South Carolina, with a rare blast of snow and ice. (AP Photo/Robert Ray) Robert Ray

  • People attend to their vehicle on Interstate 26, near Savannah, Ga., Wednesday, Jan. 3, 2018. A brutal winter storm dumped snow in Tallahassee, Fla., on Wednesday for the first time in nearly three decades before slogging up the Atlantic coast and smacking Southern cities such as Savannah and Charleston, South Carolina, with a rare blast of snow and ice. (AP Photo/Robert Ray) Robert Ray

  • Late in the afternoon Wednesday, Jan. 3, 2018, snow covers the frozen water of Lake Smith in Virginia Beach, Va. A brutal winter storm smacked the coastal Southeast with a rare blast of snow and ice Wednesday, hitting parts of Florida, Georgia and South Carolina with their heaviest snowfall in nearly three decades. (L. Todd Spencer/The Virginian-Pilot via AP) L. Todd Spencer



AP Science Writer
Thursday, January 04, 2018

When it comes to weather, it’s hard to sound scarier than “bomb cyclone.”

It’s a version of a real weather term that applies to a massive winter storm that pulled together Wednesday off the U.S. Southeast coast. But as fearsome as the storm is with high winds and some snow, it may not be quite as explosive as the term sounds.

Meteorologists have used the term “bomb” for storms for decades, based on a strict definition, said University of Oklahoma meteorology professor Jason Furtado.

After it showed it showed up in a Washington Post story on Tuesday, the weather geek term took on a life of its own on social media. The same thing happened four years ago with “polar vortex,” another long-used weather term that was little known to the public until then.

“Bombogenesis is the technical term. Bomb cyclone is a shortened version of it, better for social media,” said Weather.US meteorologist Ryan Maue, who helped popularize polar vortex in 2014.

“The actual impacts aren’t going to be a bomb at all,” Maue said. “There’s nothing exploding or detonating.”

Storm intensity is measured by central pressure — the lower the pressure, the stronger. A storm is considered a “bomb” when the pressure drops rapidly — at least 24 millibars in 24 hours.

This storm looks like it will intensify at twice that rate, said Bob Oravec, lead forecaster at the National Weather Service’s Weather Prediction Center.

So far, the storm has dumped freak snow on the Southeast. It’s aiming for the Northeast, where the snow forecast for Thursday isn’t that big a deal, Furtado and others said. The worst of this storm will stay out to sea. What is going to be bigger is the high winds — gusts exceeding 60 mph — and the bitter cold that follows, they said.

Bomb cyclones draw air from polar regions after they leave. In this case, it means extra cold Arctic air because of where the polar vortex is, Furtado said.

Worldwide, about 40 to 50 “bomb cyclones” brew each year, but most are over open ocean and nobody but weather geeks notice, Maue said.

“We use the term bomb,” Furtado said. “We know what it means, but I do think it gets a little hyped up.”

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Follow Seth Borenstein on Twitter at @borenbears . His work can be found here .