The incident happened in 2011 when heavy snow took over the American streets. Thundersnow occurs when thunder is formed from warm air which normally doesn’t happen. But still you can expect more snow in the future.
Russians experienced it in 2010 when their streets were filled with multi coloured snow. They were stunned when they found brown and purple coloured snow. The scientist checked a sample and cleared that its not toxic but warned the locals from ingesting it.