Severe thunderstorms are a product of great turmoil (instability) in the atmosphere. Instability exists when cooling occurs aloft while the surface air heats up. This generates huge columns of rising air which, when enough moisture is present, can turn into towering storm clouds. The severity of a thunderstorm is a product of its size and interaction with the jet stream.

Wednesday, strong to severe thunderstorms are expected to impact the High Plains from western Texas to Nebraska. The worst of the storms will cause violent winds, large hail and may spawn a tornado.

Story by AccuWeather.com Expert Senior Meteorologist John Kocet.