What is a bomb cyclone?

When that Arctic blast swept across the U.S. just before Christmas, The National Weather Service was predicting a “bomb cyclone.”

But what is a bomb cyclone?

According to the National Ocean Service, the term is used when a “midlatitude cyclone rapidly intensifies, dropping at least 24 millibars over 24 hours.”

Millibars are how atmospheric pressure is measured.

“Storms, of course, always have lower atmospheric pressure, but in this case, the atmospheric pressure is lowering very quickly as the storm system intensifies,” according to AccuWeather Chief Meteorologist Jon Porter.

In places like Denver, temperatures dropped about 40 degrees within an hour.

Bomb cyclones can have dangerous effects. According to The National Oceanic and Atmospheric Administration, it can cause high, intense winds that cause power outages.

Blizzard conditions with heavy blowing are also a major concern.

Some areas could also experience rainfall or snow that could cause river flooding.

By Scripps National.