WeatherTalk: Spiky hail is a sign of very strong updrafts.
Hail forms in the updraft region of a strong thunderstorm.
FARGO — It's a hot, humid summer evening until a thunderstorm strikes. As the rain becomes very heavy, there is a sudden rush of cold air as the ground is covered with balls of ice. Hail is a fascinating product of summer thunderstorms. It happens many times each summer across the region, but only in isolated, very narrow swaths, making it a relatively rare experience.
Hail forms only in the updraft region of a thunderstorm when the upward current of air is strong enough to force raindrops, and then ice balls, up into the very cold parts of the thunderstorm up high, sometimes several times, producing layers of ice which increase the size of the hail. During some storms with extremely strong updrafts, partially melted small hailstones will bump against larger hail and stick, producing unusually spiky balls of ice.