Implies a steady precipitation that might last for several hours. Severe Thunderstorm Warning - Issued to warn the public, emergency management and other cooperating agencies when a severe thunderstorm is forecast to occur or is occurring. The warning will include where the storm was occurring, its direction of movement and the primary threat from the storm. Severe Thunderstorm Watch - Issued when conditions are favorable for the development of severe thunderstorms in and close to a defined area. Shower - Intermittent rainfall of short duration that falls from a cumulus cloud.
Heavy precipitation is possible.
Implies more of a scattered rainfall. Squall Line - A line of solid or nearly solid thunderstorms or strong winds that might extend for several hundred miles. Supercell - A severe thunderstorm whose updrafts and downdrafts are in near balance allowing the storm to maintain itself for several hours. Supercells often produce large hail and tornados. Tornado - A rapidly rotating column of air extending from a cumulonimbus cloud with a circulation that reaches the ground.