Northern California braces for heavy rain from approaching bomb cyclone

Northern California is preparing for heavy rain from a "bomb cyclone." This term describes a storm that rapidly strengthens, specifically when its pressure drops at least 24 millibars within 24 hours, though this can vary by latitude. The concept originated from a 1980 research paper by MIT meteorologists, who refined earlier definitions of rapidly deepening storms. The term "bomb" reflects the explosive nature of these storms due to quick pressure drops. To determine the pressure drop for a bomb cyclone, meteorologists use a formula based on the storm's latitude. This calculation adjusts the 24 millibar requirement according to where the storm forms.