How bomb cyclones form and create dangerous conditions

By ISABELLA O’MALLEY

When turbulent weather with whipping winds and heavy snow is in the forecast, meteorologists sometimes warn that a storm could “bomb out” or become a bomb cyclone. But what exactly does this mean?

According to the U.S. National Oceanic and Atmospheric Administration, certain storms undergo bombogenesis, which happens when a storm’s central pressure drops at least 24 millibars in 24 hours. These storms are sometimes called bomb cyclones. Storm intensity is measured by central pressure, so the lower the pressure, the stronger the storm.

Such rapidly strengthening storms are capable of producing heavy rain, blizzard conditions and intense winds that can create dangerous conditions such as downed trees and power outages.

“If you’re watching TV at night and the weather report comes on and you’re hearing ‘bomb cyclone’ being used, that usually means there’s quite a bit of active weather going on,” said Andrew Orrison, a meteorologist with the National Weather Service in College Park, Maryland.

Bomb cyclones can happen in any season, but mainly occur during fall and winter when frigid air from the Arctic can creep south and clash with warmer air masses.

“It’s really the clash of those air masses that really kind of helps to generate the areas of low pressure in the first place,” said Orrison.

Regions in North America that are prone to seeing bomb cyclones include Alaska, the Pacific Northwest and the Great Lakes region.

“It’s not common to get bomb cyclones at lower latitudes. So generally speaking, you wouldn’t see a bomb cyclone across, let’s say, the southern United States,” said Orrison.

The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.