The winter precipitation event last week had a surprise for some people. Instead of the quiet, fluffy flakes usually associated with a snowfall, a few people were treated to rumbles of thunder. So, was it a snowstorm or a thunderstorm? A storm event is generally characterized by the most destructive component of the storm: for example, wind storm, hail storm or ice storm. Generally, an observer would record the event as a thunderstorm, with the precipitation type as snow. Some people get around the question by calling it thunder snow. The combination of a thunderstorm and a snow storm is fairly unusual, but not necessarily a once-in-a-life time event. Freezing rain, ice pellets, and snow combined with thunder is also a possibility. Regardless of its rarity, the combination of the quiet snowflakes and the clash of thunder make for a very memorable weather wonder.
Mary Knapp, Weather Data Library