Freezing Weather and Thundersnow

http://www.almanac.com/blog/weather-blog/freezing-weather-and-thundersnow

On November 17 a massive cold spell brought freezing weather to 49 states. Only Hawaii wasn’t engulfed by the cold and even that sunny state had 31°F weather on the top of Mt. Kea. The massive freeze lingered for days. As noted in my last blog, the abnormally cold polar air mass is suspended just north of us and like the sword of Damocles, it takes very little to encourage it to fall south.
This year, however, the cold is bringing not just cold, misery and snow, but also rare thundersnows—thunderstorms that produce snow instead of rain. High winds, as strong as a tropical storm whip the land. Even worse, this weather event typically brings an additional six inches of snow. Then, when everything melts, a high risk of floods.