Everything You Need To Know About Bomb Cyclones

  • A bomb cyclone is an area where a low pressure system rapidly strengthens.
  • It comes from the weather term “bombogenesis”.
  • To be classified as a bomb cyclone, the central pressure of the low-pressure system must drop by at least 24 mbar in 24 hours.
Bomb cyclones are more and more commonly used in winter to describe powerful low pressure systems that intensify rapidly and are often accompanied by heavy snow and strong winds.

You might think the term was coined for public attention, but it actually has roots in meteorology.

Derived from bombogenesis

The term “bomb cyclone” comes from the meteorological term “bombogenesis,” which refers to the central pressure of a low-pressure system that drops at least 24 millibars within 24 hours. The American Meteorological Society’s Glossary even defines it this way.

Simply put, this means that the storm is intensifying rapidly and can have more severe effects than a weaker storm would produce.

A satellite view of Winter Storm Grayson after it became a bomb cyclone along the East Coast in January 2018.

Bomb cyclones aren’t common, but they’re not rare either

A 2021 study led by Robert Fritzen of Northern Illinois University found that about 7% of non-tropical cyclones that formed near North America between 1979 and 2019 were bomb cyclones. This equates to an average of about 18 bomb cyclones per year near North America in its 40 years.

They are most common in the East, but can occur elsewhere in the United States

The majority of bomb cyclones occurred off the east coast of the United States, with an average of one such bomb cyclone per year.

In the northeast, bombogenesis occurs when there is a large temperature gradient between the cold continental air mass in the Atlantic Ocean and the warm sea surface temperature.

Beyond that temperature difference, a powerful and intensifying jet stream disturbance lifts the air and initiates the bombogenesis process.

Nor’easter is often a bomb cyclone when the cold air sweeping south from Canada combines with the warm ocean waters of the Gulf Stream.

Bomb cyclones occur most frequently near the East Coast, but can occur elsewhere, like the A bomb cyclone in the central United States that hit the West Coast in the fall of 2021.

Blast cyclones usually form in cold months

These severe storms are most common from October to March, but can occur at any time of the year.

That goes back to the fact that these storms get their fuel from temperature contrasts and the aforementioned powerful jet stream turbulence. Both of these ingredients are commonly found in the cooler months.

Effects of bomb cyclones on storm impact

Winds will increase dramatically, and precipitation, including snowfall, is likely to be heavy. Blizzard conditions can occur, and even lightning when the system is bombing.

Gusts of wind often exceed 50 miles per hour, especially in open land and near the East Coast and Great Lakes shorelines. These strong gusts can topple trees, drain power, push water ashore, and cause coastal and lakeshore flooding.

Examples of Notable Bomb Cyclones in the Past

– In early March 2018, Winter Storm Riley, the first of the so-called four Easter holidays, bombed off the East Coast, causing devastating coastal flooding in parts of the East Coast.

– Two months earlier, in early January 2018, Winter Storm Grayson intensified in the Western Atlantic at its fastest rate on record, declining by about 59 millibars in 24 hours to a low of 950 megabytes.

– In February 2013, Winter Storm Nemo dropped 29 mb within 24 hours (specifically, 1,000 mb of pressure was recorded at 4am on February 8, and 971mb at 4am on February 9). mb). The Winter Storm Nemo finally “bottomed out” on February 9th at 4pm with a minimum pressure reading of 968 mb. small island.

– An example of a land-based bombing is the Octobomb, which affected parts of the Plains and Midwest on October 25-27, 2010. Minnesota and Wisconsin set the lowest barometric pressure readings ever recorded by the system.

– March 2019 saw another big bomb cyclone in the central United States. That system, named Winter Storm Almaa, brought heavy snow, flooding rains, and destructive winds to the plains.

Color-enhanced water vapor satellite image of the most intense Plains Bomb Cyclone – Winter Storm Ulmer – on March 13, 2019.


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