'Bomb cyclone': How it creates a big snowstorm

Thursday’s snowstorm has not only delivered a winter beating to Long Island, but also comes with a funky weather term — bombogenesis.

While it may sound like a prog rock group, the term actually applies to a storm in which the air pressure decreases rapidly, whipping up winds and thickening the snowfall. In this case, the storm, which some forecasters are calling a “bomb cyclone” or “snow hurricane,” is dropping a foot or more of snow on Long Island Thursday. That’s along with damaging winds, bone-chilling temperatures and a chance of coastal flooding.

“It is defined as a meteorological bomb,” said Chris Stachelski, a meteorologist for the National Weather Service in Upton. “It’s a very, very powerful storm.”

“Hurricane hunter” planes were flying into the storm to help create forecast models, added News 12 Long Island meteorologist Richard Hoffman.

Here’s a quick breakdown on bombogenesis:

What is bombogenesis? Technically, it’s defined as a storm in which the air pressure drops 24 millibars or more in 24 hours. The air pressure in this storm was expected to drop 30 millibars over that period, Stachelski said. It’s not a freak occurrence, as this region gets one or two such storms each winter, he said.

Can you feel the pressure dropping? Stachelski said some people claim that bombogenesis can send women into labor or crank up arthritis. But he’s not sure about that.

What causes it? Several conditions are coming together in this “storm bomb.” For example, the jet stream is carrying cold air over warm water. That clashing of cold arctic air with the warmer Gulf Stream creates a chimney effect where the warm air rises rapidly and the air pressure drops. “And then we have a snowstorm,” said Tim Morrin, another Weather Service meteorologist.

What happens after? Temperatures will remain below freezing through the weekend, with Friday and Saturday especially frigid, but start to rise above freezing on Monday, Stachelski said.