European Severe Weather Database
ESWD
Version 4.2.2   (20 Dec 2013)

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Definitions

dust devil   
A vortex not associated with a convective storm, typically between a few metres to a few tens of metres in diameter, extending upward from the earth's surface but not reaching any cloud. It is rendered visible by material lifted off the earth's surface (land devils) or by water droplets (water devils). Lesser whirlwinds result from temperature differences between the surface and the air above. Whirls in the lee of objects (e.g. buildings) are not considered a 'lesser whirlwind' here.   

funnel cloud  
A cone or tube-shaped downward extension of a convective cloud caused by a rapidly rotating vortex, not reaching the earth's surface.  

gustnado
A vortex occurring along a gust front of a convective storm that is visible by material that is lifted off the earth's surface. It is typically a few metres to a few tens of metres in diameter and extends upward from the earth's surface but is not connected with a cloud. In case of uncertainty whether a gustnado really occurred, do not select gustnado. If it is certain that either a tornado or gustnado occurred, select "tornado". If a "severe wind gust" may have occurred instead of a gustnado, please select that group.

heavy rain  
Heavy rain defined here as rain falling in such large amounts, that significant damage is caused, or no damage is known, but precipitation amounts have been observed that are exceptional for the region in question.  

large hail    
The falling of hailstones having a diameter (in the longest direction) of 2.0 centimetres or more and/or smaller hailstones that form a layer of 2.0 cm thickness or more on flat parts of the earth's surface.    

tornado 
A tornado or waterspout is a vortex typically between a few metres to a few kilometres in diameter, extending between a convective cloud and the earth's surface, that may be visible by condensation of water and/or by material (e.g. water, in case of a waterspout) that is lifted off the earth's surface.

Remark: select "tornado or waterspout" when a tornado or waterspouts is likely to have occurred or in case of doubt between a tornado or gustnado. If it is possible that a "severe wind gust" has occurred instead, select that category. 

severe wind    
A severe wind gust is a gust measured to have a speed of at least 25 m/s or one doing such damage that a wind speed of 25 m/s or higher is likely to have occurred.    

heavy snowfall/snowstorm    
Snow (or snow grains) and/or snowstorm in an amount that causes - or is capable of causing - important disruptions of daily life and/or considerable material or economical damage.    

ice accumulation    
Accumulations of ice on the earth’s surface and/or objects (such as power lines) in an amount that causes - or is capable of causing - important disruptions of daily life and/or considerable material damage or economical damage, not including ice accumulations resulting primarily from snowfall. Ice accumulations may result from freezing rain, freezing drizzle, freezing fog or from direct deposition of water vapour, resulting in glaze, frost or rime.    

avalanche    
A rapid flow of snow down a slope.    

damaging lightning    
A lightning strike causing important damage to aircraft, vehicles, ships, or injuring/killing people or animals. Ball lightning or other exceptional lightning phenomena can be reported in this category also if no damage was reported.