Really good ones are known as supercells: that's a severe thunderstorm with a constant flow of warm air.

The last two days have been stormy, with gales and a severe thunderstorm over all parts of the front.

They are most often associated with a localized low-pressure region within a severe thunderstorm.

Although a severe thunderstorm warning was issued at 2:57 pm, very few people received the warnings in time.

Combined with ground reports, tornado and severe thunderstorm warnings can be issued to alert the public about dangerous storms.