What is a 'bomb cyclone'?

A powerful storm is bearing down on the West Coast and bringing with it a scary-sounding weather term - bomb cyclone. Bomb cyclone is a term used by weather enthusiasts to describe a process that meteorologists usually call bombogenesis. It’s the rapid intensification of a cyclone in a short period of time, and it can happen during powerful storms such as the one are preparing for this week.

But what is a bomb cyclone, why does it happen and why are these big storms so feared? What is a bomb cyclone? A bomb cyclone occurs during the rapid intensification of a cyclone located between the tropics and the polar regions, according to the National Oceanic and Atmospheric Administration. It can happen when a cold air mass collides with a warm air mass, which is something that can occur over ocean waters, the agency says. The measurement needed to determine whether a cyclone can be can be tricky, but it largely concerns a swift drop in pressure.

Atmospheric pressure is measured in millibars by the National Weather Service. If a storm decreases 24 millibars or more in 24 hours or less, it can be considered a bomb cyclone, said Stephen Baron, a forecaster with the weather service in Gray, Maine. “I would say rapid intensification of hurricanes is one of the more common times we see it,” Baron said.

“We do see it with Nor’easters occasionally.” Why is it happening on the West Coast? The National Weather Service Weather Prediction Center has issued excessive rainfall risks s.