Bomb cyclone hits eastern U.S.

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Bomb cyclone hits eastern U.S.

  • Blinding snow whipped up by powerful winds struck the eastern United States on Saturday, as one of the strongest winter storms in years triggered transport chaos and power outages across a region of some 70 million people.
  • Major cities like New York and Boston bore the brunt of the blizzard, which the National Weather Service (NWS) confirmed intensified on Saturday into a “bomb cyclone” - characterized by the explosive power of rapid drops in atmospheric pressure.


  • Explosive cyclogenesis (also referred to as bomb cyclone) is the rapid deepening of an extra-tropical cyclonic low-pressure area.
  • This is a predominantly maritime, winter event, but also occurs sometimes in the summer.
  • It is a term used by meteorologists to indicate a mid-latitude cyclone that intensifies rapidly.
  • A bomb cyclone happens when atmospheric pressure in the middle of the storm drops at least 24 millibars over 24 hours, quickly increasing in intensity.
  • The lower the pressure, the stronger the storm.

Factors affecting Bomb Cyclone

  • Vorticity Maxima: explosive cyclogenesis events tend to occur in association with large amplitude 500 hPa vorticity maxima.
  • Baroclinicty: increased baroclinicty helped to strengthen both the jetstream and the vorticity advection, which helped to further deepen and thus strengthen the bomb cyclone.
  • Jet Stream and topography: while the jetstream helps to provide the instability needed for a bomb cyclone to develop, it’s the topography of the East Coast that acts as a focusing and triggering mechanism.

Formation Mechanism

  • A bomb cyclone forms when air pressure rapidly drops as the storm explosively strengthens.
  • And typically, the lower the pressure, the stronger the storm.
  • Baroclinic instability has been cited as one of the principal mechanisms for the development of most explosively deepening cyclones.
  • Other factors include:
  • The relative position of trough and thickness patterns,
  • Deep tropospheric frontogenetic processes which happen both upstream and downstream of the surface low,
  • The influence of air–sea interaction, and
  • Latent heat release.
  • This process is the extratropical equivalent of the tropical rapid deepening.
  • Although their cyclogenesis is entirely different from that of tropical cyclones, bomb cyclones can also produce winds of 120 to 155 km/h and yield heavy precipitation.

How it works?

  • Deep drops in barometric pressure occur when a region of warm air meets one of cold air.
  • The air starts to move and the rotation of the earth creates a cyclonic effect.
  • The direction is counterclockwise in the Northern hemisphere leading to winds that come out of the northeast.

Region of occurrence

  • The four most active regions where extra-tropical explosive cyclogenesis occurs in the world are-
  • the Northwest Pacific,
  • the North Atlantic,
  • the Southwest Pacific, and
  • the South Atlantic

Impact of Bomb Cyclone

  • Violent strong winds– wind speed is quiet strong and severe.
  • Blizzard/ Heavy Snowfall– at times the snowfall may be up to 1 foot.
  • Flood– the rainfall is with very high intensity causing severe floods.
  • Damage to Flora and Fauna– causes uprooting of trees, habitat loss for animals etc.
  • Damage to infrastructure– collapsing of buildings and other public infrastructures.
  • Social damage– loss of residence and lives of humans.
  • Economic losses– economic loss is too large to be estimated.
  • Bomb cyclones draw air from Polar Regions after they leave– hence severe cold winds enters the region.

Difference between hurricanes, cyclones and typhoons

  • Hurricanes, cyclones and typhoons are all tropical storms.
  • They are all the same thing but are given different names depending on where they appear.
  • When they reach populated areas they usually bring very strong wind and rain which can cause a lot of damage.
  • Hurricanes are tropical storms that form over the North Atlantic Ocean and Northeast Pacific. Cyclones are formed over the South Pacific and Indian Ocean.
  • Typhoons are formed over the Northwest Pacific Ocean.


  • A warming world has increased the possibility of the occurrence of such intense storms, though scientists say that directly attributing this storm to climate change would not be possible at this point in time.
  • Even though only a minority of the bombs become so strong, some have caused significant damage.