Move over Snowmageddon and make way for the “bomb cyclone” which hit the East Coast January 4, 2018. While the official name of this winter storm is “Grayson”, the media focused on the phenomenon (bombogenesis) that increased Grayson’s wrath and fury, converting it from a run-of-the-mill Nor’easter into a “bomb cyclone.”
What the heck is a “bomb cyclone”? Many born-and-bred New Englanders have commented over the last few days that even they have not heard of this term. A “bomb cyclone” refers to a phenomenon that occurred as this weather event unfolded. The official term is “explosive cyclogenesis,” or “bombogenesis.” The “bombing” occurs when a low-pressure system’s central pressure falls below a certain threshold (measured in millibars) in 24 hours or less. A low pressure system occurs where the atmospheric pressure at sea level is lower than the surrounding land area. The bomb part comes into play because the pressure (the force exerted by the air’s weight) drops significantly – the lower the pressure drops within a cyclone, the more intense a storm it creates.