Bomb Cyclone Threatens East Coast After Massive Snowstorm Hits Most of Nation

Or it could deliver a glancing blow, mostly striking places like Cape Cod. Alternatively, it could veer off harmlessly to sea. Meteorologists and forecast models aren’t yet settling on a single outcome.

The National Weather Service said a bomb cyclone occurs when a midlatitude cyclone rapidly intensifies during a 24-hour period, typically when a cold air mass collides with a warm air mass, such as air over warm ocean waters. “This intensification is represented by a drop in millibars, a measurement of pressure used in meteorology,” NWS said. At 60 degrees latitude, it requires a drop of at least 24 millibars over 24 hours. At the latitude of New York City, the required pressure drop is about 17.8 millibars over 24 hours.

As for the cold temperatures, the next blast of Arctic air surges south down the Plains, across the Great Lakes and through the Southeast and East. “This could be longest duration of cold in several decades,” the NWS said. “Forecast models are being closely monitored for potential of another significant winter storm to impact the eastern United States this coming weekend. Confidence in coastal impacts has increased.”

The uncertainty about the storm’s path means coastal cities face difficult preparation decisions. Do they preemptively mobilize resources for a major storm that might miss them, or wait for more certainty and risk being caught unprepared?