A bomb cyclone struck Friday as a massive winter storm pummeled much of the central and eastern United States with heavy snowfall, high winds and dangerous temperatures, affecting millions of Americans in its path. Meanwhile, flooding threatens the northeast. The storm is scrambling holiday travel plans and prompting warnings from officials to take precautions.
Whenever meteorologists mention the weather phenomenon known as a bomb cyclone, Google searches for the phrase begin to rise, and we’re seeing the same trend this week.
Here’s what you need to know about bomb cyclones and how you can prepare for them.
What is a bomb cyclone?
A bomb cyclone, also known as a bombogenesis, is a rapidly developing storm that occurs when atmospheric pressure drops by at least 24 millibars over a 24-hour period, the National Oceanic and Atmospheric Administration notes online.
“A bomb cyclone occurs when the atmospheric pressure at the center of the cyclone drops rapidly. In order to qualify as approximately, the pressure must drop by approximately 1 [millibar]or more, every hour for a 24-hour period,” John Moore, a public affairs specialist and meteorologist with the National Weather Service, told CBS News.
“This can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters,” explains NOAA.
Why is a cyclone called a bomb?
The popular term was first used around the 1940s, according to Mike Bettes, meteorologist for The Weather Channel.
“It’s called a bomb cyclone because a low pressure (or cyclone) undergoes ‘bombogenesis,’ which refers to the rapid rate at which low pressure develops,” Bettes told CBS News.
What are the effects of a bomb cyclone?
The dangers of a bomb cyclone can be multifaceted and vary depending on the location and speed of the storm. According to the agency, the band of intense pressure can create strong winds, blizzard conditions (heavy snow that can possibly reduce visibility) and rain. Heavy rainfall can also cause coastal flooding.
“In winter, heavy snowfall and extreme winds can be experienced. It generally leads to very dangerous travel conditions with blown and drifting snow and poor visibility. Airlines often cancel flights because the conditions are too dangerous to fly. High winds can often lead to widespread outages,” Bettes said.
Mixing cold temperatures with strong winds can create dangerous wind chills, increasing the risk of frostbite.
Moore said a bomb cyclone can also cause a ripple effect from other weather events.
“There may also be strong temperature drops along the frontal boundary associated with some bomb cyclones. There may also be thunderstorms along the frontal boundary in the warm sector of the storm,” Moore noted.
What is a “bomb cyclone?” 01:05
When do bomb cyclones occur most often?
Although bomb cyclones can occur at any time of the year, they tend to be reported most frequently in the winter months. They are most common from December to early March, according to a 2017 study in the Journal of Applied Meteorology and Climatology that analyzed patterns of bomb cyclones in the North Pacific Ocean from 2000 to 2015.
Moore says the same is true today.
“Bomb cyclones often occur more during the cold season,” he agreed.
How to prepare for a bomb cyclone
Whenever a storm is predicted to hit your area, you need to make sure you’re prepared.
Stay up-to-date on the weather forecast for your region, stock up on enough emergency supplies to last several days, and make sure your home is protected.
“If you expect impacts similar to a winter storm, prepare accordingly. If you live near a coastal area, coastal flooding could have an impact. Heavy rains associated with a bomb cyclone could also cause flooding , so those who live in areas that are susceptible to flooding should be on alert,” Moore said.
Bettes echoed Moore’s advice and encouraged people in the direct path of a bomb cyclone to stay home.
“In the event of a power outage, people should only use a generator as provided in the instruction manual and never use a generator indoors. Also, consider having a heat source of reservation that does not involve an open flame,” he added.
What causes bombogenesis? 01:41