Precipitation in the form of balls or irregular lumps of ice more than 5mm in diameter, always produced by convective clouds, nearly always cumulonimbus.

A National Weather Service (NWS) Weather Forecast Office (WFO) product issued when either a severe thunderstorm is indicated by radar or a spotter reports a thunderstorm producing hail one inch or larger in diameter and/or winds equal or exceed 58 miles an hour. They are usually issued for a duration of 30 minutes to one hour. Lightning frequency is not a criteria for issuing a severe thunderstorm warning. If the severe thunderstorm will affect the nearshore or coastal waters, it will be issued as the combined product--Severe Thunderstorm Warning and Special Marine Warning.

A violently rotating column of air, in contact with the earth's surface, either pendant from a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud. When tornadoes do occur without any visible funnel cloud, debris at the surface is usually the indication of the existence of an intense circulation in contact with the ground. See also landspout and waterspout.

A National Weather Service (NWS) Weather Forecast Office (WFO) product issued when when a tornado is indicated by weather radar or sighted by spotters. They are usually issued for a duration of 30-45 minutes. If the tornado will affect the nearshore or coastal waters, it will be issued as the combined product--Tornado Warning and Special Marine Warning. See also tornado emergency.