Thundersnow, also known as a winter thunderstorm or a thunder snowstorm, is a relatively rare kind of thunderstorm with snow falling as the primary precipitation instead of rain. It typically falls in regions of strong upward motion within the cold sector of an extratropical cyclone, where the precipitation consists of ice pellets rather than snow. Snowstorms that trigger lightning are rare. Of the roughly 10,000,000 cloud-to-ground lightning flashes observed over the continental United States each year, about 0.1 percent to 0.01 percent are associated with snow, says Walter Petersen, atmospheric physicist with NASA’s Marshall Space Flight Center in Huntsville, Alabama. This thundersnow happened this winter in northern Alabama and was observed first hand by sophisticated lightning mapping station in Huntsville