Philadelphia Moving

The massive nor'easter pummeling the East Coast has strengthened rapidly today, undergoing what's known as bombogenesis or "bombing out."

Dubbed a "bomb cyclone," the catchphrase was coined earlier this year as a nickname for another nor'easter back in early January.

Bombogenesis -- or a "bomb cyclone" -- occurs when the pressure of a storm drops 24 millibars in 24 hours, or at the rate of 1 millibar per hour. (A millibar is a measure of atmospheric pressure inside a storm, telling meteorologists how strong or weak the storm system is).

It usually happens when a storm system moves over the warm waters of the western Atlantic Ocean and the Gulf Stream at the same time that arctic air moves in from behind. The Northeast coast of the United States experiences this at least once a year.

The difference between the two air masses helps to strengthen the storm system, creating what's known as bombogenesis.

As a storm system moves over the Gulf Stream off the East Coast, it picks up all the available moisture and dumps it in the form of snow if there is enough cold air in place.

The lower the storm's pressure, the stronger the winds are around the storm. This week's strong winds could wreak havoc, bringing major power outages and coastal flooding for Northeast coastal cities.