Severe Storm

Cyclone Idai on 13 March 2019 west of Madagascar and heading for Mozambique. Image: ESA.

Definition

Storms are generally classified as a meteorological hazard,  caused by short-lived, micro- to meso-scale extreme weather and atmospheric conditions that last from minutes to days (EM-DAT).

Facts and figures

There are several different types of storms distinguished by the strength and characteristics of atmospheric disturbances:

  • Convective/local storm: A type of meteorological hazard generated by the heating of air and the availability of moist and unstable air masses. Convective storms range from localized thunderstorms (with heavy rain and/or hail, lightning, high winds, tornadoes) to meso-scale, multi-day events.
  • Sandstorm, dust storm: Strong winds carry particles of sand aloft, but generally confined to less than 50 feet (15 metres), especially common in arid and semi-arid environments. A dust storm is also characterised by strong winds but carries smaller particles of dust rather than sand over an extensive area.
  • Tornado: A violently rotating column of air that reaches the ground or open water (waterspout).
  • Lightning: A high-voltage, visible electrical discharge produced by a thunderstorm and followed by the sound of thunder.
  • Winter storm, blizzard: A low pressure system in winter months with significant accumulations of snow, freezing rain, sleet or ice. A blizzard is a severe snow storm with winds exceeding 35 mph (56 km/h) for three or more hours, producing reduced visibility (less than .25 mile (400 m).
  • Orographic storm (strong wind): Differences in air pressure resulting in the horizontal motion of air. The greater the difference in pressure, the stronger the wind. Wind moves from high pressure toward low pressure.  
  • Extratropical storm: A type of low-pressure cyclonic system in the middle and high latitudes (also called mid-latitude cyclone) that primarily gets its energy from the horizontal temperature contrasts (fronts) in the atmosphere.
  • Tropical storms: A tropical cyclone originates over tropical or subtropical waters. It is characterised by a warm-core, non-frontal synoptic-scale cyclone with a low pressure centre, spiral rainbands and strong winds. Depending on their location, tropical cyclones are referred to as hurricanes (Atlantic, Northeast Pacific), typhoons (Northwest Pacific), or cyclones (South Pacific and Indian Ocean) (UNDRR, Sendai Framework).

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Event

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News

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Publishing date: 22/07/2019
Regional Support Offices mentioned:
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According to a new study by scientists from NASA and NOAA, tropical cyclones stall more frequently and stay longer near the coastline. This potentially leads to more precipitation over confined locations and thus an aggravation of tropical cyclone hazards for coastal populations.

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Publishing date: 04/07/2019
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Publishing date: 04/07/2019
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Publishing date: 01/07/2019
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Millions of people in Mozambique, Malawi and Zimbabwe are struggling to cope with the aftermath of Cyclone Idai, which has swept through this part of southeast Africa over the last weeks, leaving devastation in its wake. It is thought that more than two million people in the three countries have been affected, but the extent of destruction is still unfolding.

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Publishing date: 04/04/2019
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Publishing date: 18/03/2019

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Data Source

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