During last week’s lake effect snowstorms in western New York, there were several instances of thunder and lightning during the heavy snowfall.  Although not something witnessed routinely, thundersnow is not some freak of nature.  I have personally seen lightning during snowfall four or five times in my life.  Lightning is a product of a convective shower. Electrical charge is built up as raindrops and snowflakes bounce around and interact in the rapidly rising air within an updraft.  Most snowfalls come from larger-scale, general rising motions.  Showers are more common in warm weather when the air tends to be more unstable.  Lake effect snows are ideal for thundersnow because the cold air flowing over warmer water can produce the necessary instability.  But sometimes, even out here on the Great Plains, showers form in air cold enough to produce snow, and thundersnow can be the result.      Meteorologist John Wheeler