Strong thunderstorms can produce balls or irregular lumps of ice that fall to the ground as hail. The stones form when supercooled water freezes onto ice particles that are kept aloft by powerful updrafts. Each cycle through the cloud adds another layer of ice.

Hailstones range from pea size to larger than softballs in extreme cases. The largest stones require sustained updrafts exceeding 100 miles per hour. When the stones grow too heavy for the updraft to support, they fall, sometimes melting partially on the way down.

Hail damages crops, vehicles, and roofs. Severe thunderstorms that produce large hail are often also capable of damaging winds or tornadoes. Radar can detect the presence of hail through distinctive signatures, allowing warnings before the stones reach the ground.

Accumulation of hail can briefly turn summer landscapes white.