Ice pellets

Ice pellets (also referred to as sleet by the United States National Weather Service[1]) are a form of precipitation consisting of small, translucent balls of ice. Ice pellets are usually smaller than hailstones[2] and are different from graupel, which is made of rime, or rain and snow mixed, which is soft. Ice pellets often bounce when they hit the ground, and generally do not freeze into a solid mass unless mixed with freezing rain. The METAR code for ice pellets is PL.

http://en.wikipedia.org/wiki/Ice_pellets