The National Weather Service’s Weather Prediction Center said the developing “significant” storm system will first bring snow over the Cascades before spreading over the Northern Rockies into the Upper Midwest by midweek. Forecasters are warning of a rare April blizzard which could see over a foot of snow and the risk of flooding. The storm is building in the Pacific ocean, and is expected to intensify and form a ‘bomb cyclone’ inland, which could affect up to 200 million Americans by the end of the week, according to Accuweather.
What is a bomb cyclone?
A bomb cyclone – officially called ‘explosive cyclogenesis’ or ‘bombogenesis’ – is a rapid drop in air pressure.
To classify, the air pressure must drop 24 millibars in 24 hours.
This rapid drop in pressure intensifies the power of the storm, creating hurricane-like conditions, even though the formation is totally different.
In the 1940s and 1950s, meteorologists at the Bergen School of Meteorology began informally calling some storms that grew over the sea “bombs” because they developed with a great ferocity rarely seen over land.
The term ‘bomb’ is used as the development is explosive, with the quick drop in pressure, rather than slowly building like a hurricane or tropical cyclone.
Impacts from a bomb cyclone can include strong winds, heavy rains and snow, sea swell and flooding.
AccuWeather senior meteorologist Alex Sosnowski said: “The term bombogenesis comes from the merging of two words: bomb and cyclogenesis.
“All storms are cyclones, and genesis means the creation or beginning.
“In this case, ‘bomb’ refers to explosive development. Altogether the term means explosive storm strengthening.”
The four most active regions where extratropical explosive cyclogenesis occur in the world are the Northwest Pacific, the North Atlantic, the Southwest Pacific, and the South Atlantic
What should you expect?
If you’re caught in the path of a bomb cyclone, you could expect to see intense wind gusts or large amounts of snow.
John Gyakum, a professor of atmospheric science at McGill University in Montreal, told The Washington Post: “The name isn’t an exaggeration.
“These storms develop explosively and quickly.
“They can produce destructive winds, coastal flooding and erosion, and, of course, very heavy precipitation.
“If the term conveys the importance and the danger associated with them, then I think that’s a good thing.”