Thundersnow! What is thundersnow and what causes it? Thundersnow is a rare winter storm event that occurs when thunder and lightning happen during a snowstorm. ... If it all comes together, that enhanced upward motion of air increases snow growth and causes enough electrical charge separation within the cloud for lightning to strike, according to abc news in a story published on March 7 2018. Other than being cool to experience and look at, what do you know about weird weather phenomena's? What ever type of storm damage you incur, know that the team at SERVPRO of Pottstown/Souderton is here and ready to help! We are one team and we care about our communities. You can reach us at our office line 24/7 at 610-327-9644.