The Bomb Cyclones

By Ian Teñido


As scary as the name is so are the people hearing about it for the first time. What the heck is a ‘Bomb Cyclone’? This is the question that my colleague asked which prompted me to have an article about it. The name really sounds cool but at the same time kinda scary… Cool in the sense that it depicts the force of its occurrence and scary when someone thinks about getting caught in the middle of such a ‘bomb cyclone.’ There are numerous names attached to this kind of occurrence. From the meteorological definitions, the synonyms include:

  • Explosive cyclogenesis
  • Weather bomb
  • Meteorological bomb
  • Bomb genesis
  • Explosive development

All the above names refer to a rapidly deepening extratropical cyclonic low-pressure area. This brings me back to some geography again. When the storms were being assigned names by meteorologists, it happened that this kind of storm would also be called a bomb cyclone. Back in 1940s and 50s, the meteorologists at Bergen School of Meteorology began calling, very informally, the storms occurring over the sea as ‘bombs.’ The reason for this tendency is because the storms over the sea developed with a great ferocity (brutality/aggression). Over time, it led to the use of the highlighted synonyms herein. The regions in which such storms occur include the Northwest Pacific, the North Atlantic, the Southwest Pacific, and the South Atlantic.

ABC News

The bombing aspect of the cyclone occurs when a low pressure system falls (with its central pressure falling 24 millibars in 24 hours or less). To better understand how this occurs, do you recall the low and high pressure systems that lead to formation of storms or rather movement of winds; probably from high pressure to low pressure systems?  If you can recall that then you will not have an issue understanding this. A low pressure system is a region where the pressure of the atmosphere at sea level is lower than the pressure in the surrounding area. Around this low pressure region, the winds converge and rotate in the same direction as the earth thus forming a cyclone in the center of the low pressure system. By the way, a cyclone is a system of winds rotating inwards to an area of low system. The continuous circulation of winds makes air to move higher up in the atmosphere where the moisture condenses to form precipitation.


What makes a cyclone a bomb depends on the amount of fall in the atmospheric pressure.  A fall of about 24 millibars in less than a day is very rare and is considered explosive when it occurs. Grayson is probably the biggest storm of the year, as well known to many. It affects the land from Florida to Maine. The precipitation from the bomb cyclone recently hit Massachusetts and caused a lot of flooding. The flood waters took over the sidewalks and streets, cars were trapped and the subway stations were shut down. Probably, the severity of the floods and followed by a snow storm exceeded the region’s benchmark storm. Of course, this leads to massive destruction of property and unlike the normal precipitation; it can lead to numerous deaths. For the takeaway, the dilemma with such cyclones is that you never know if you are adequately prepared as witnessed so far…


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