what do you call it when it's snowing and lightning
Thundersnow is a snowstorm event in which thunder and lightning occur. An example is the classic 2011 thundersnow in Chicago that surprised Jim Cantore. Thunderstorms accompanied by snow are usually of a different character than the normal thunderstorm. The latter are usually rather tall, narrow storms containing a rising updraft of warm, moist air that has risen in a layer from near the surface that may go upward to 40,000 feet or more.