A thunderstorm with a persistent rotating
updraft . Supercells are rare, but are responsible for a remarkably high percentage of severe weather events - especially
tornadoes , extremely large hail and damaging
straight-line winds . They frequently travel to the right of the main environmental winds (i.e., they are
right movers ). Radar characteristics often (but not always) include a
hook or
pendant , bounded weak echo region (
BWER ),
V-notch ,
mesocyclone , and sometimes a
TVS . Visual characteristics often include a
rain-free base (with or without a
wall cloud ),
tail cloud ,
flanking line ,
overshooting top , and
back-sheared anvil , all of which normally are observed in or near the right rear or southwest part of the storm (see picture)
Storms exhibiting these characteristics often are called classic supercells; however
HP storms 
and
LP storms 
also are supercell varieties.
