One evening in late '84 in Northern Virginia (near D.C.) as a youth, I vividly remember a heavy squall line/thunderstorm pushing through the area,
and within 10 minutes the heavy thunderstorm changed over to heavy snow! Thunder and all!
It was the only time in my life that I've seen this phenomenon. It's rare, but it does happen!
[edit on 20-3-2010 by ghr54321]