Graupel

Graupel (; ), also called soft hail or hominy snow or granular snow or snow pellets or popcorn snow, is precipitation that forms when supercooled water droplets in air are collected and freeze on falling snowflakes, forming balls of crisp, opaque rime.

Graupel is distinct from hail and ice pellets in both formation and appearance. However, both hail and graupel are common in thunderstorms with cumulonimbus clouds, though graupel also falls in winter storms, and at higher elevations as well. The METAR code for graupel is GS. Provided by Wikipedia