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.