Hail is a byproduct of severe thunderstorms and tornadoes. It is produced when updrafts within a storm carry water droplets to a height in the sky where freezing occurs. These ice particles continue to grow as they may be dropped and picked up again, adding another layer of ice to the droplet. Eventually the hail becomes too heavy for the updraft to support and falls to the ground. With a diameter of 0.75 inch or greater, hail is considered to be severe.
Hail occurs during severe thunderstorms and tornadoes so look and listen for warning information about these storms. Large hail is often observed immediately north of a tornado, but the presence of hail doesn’t always mean a tornado, and the absence of hail doesn’t mean there is no risk of tornadoes.