A massive winter storm that will “in many ways resemble a hurricane” is expected to hit the East Coast of the US, bringing heavy snow and some of the coldest temperatures in more than a century.

Weather experts predict it will become a “bomb cyclone” because the system’s pressure is expected to fall very rapidly and create one of the most intense winter storms the US has seen in decades. The National Weather Service (NWS) has issued winter-storm watches in warnings for the entire East Coast, from Florida to Maine, with the impact felt overnight and throughout the majority of the day (January 4).

The storm, dubbed “Winter Storm Grayson,” will be similar in size and strength to a hurricane. Strong, damaging winds, possibly up to 50 miles per hour, are expected to bring down trees and power lines in the northeast, but the most extreme conditions are expected to stay off the coast.

There are already reports of icy roads in Florida and Georgia. Forecasters expect blizzard conditions in Boston, Massachusetts (and in all of Maine and New Hampshire), freezing rain in Charleston, South Carolina, southern Georgia and northern Florida, where some snow has fallen.

A bomb cyclone forms as a result of bombogenesis, also called explosive cyclogenesis, which describes how the pressure in a cyclone quickly falls, dropping at least 24 millibars of atmospheric pressure in 24 hours. Pressure drops when a mass of cold air collides with a warm-air mass, typically over ocean water. The quicker and more significant the drop in pressure, the more powerful the storm.