WATCH: 'Steamnado' pops up over Lake Lewisville during winter storm

A so-called 'steamnado' popped up over Lake Lewisville on Saturday as the winter storm impacted weather across North Texas. FOX 4 chief meteorologist Dan Henry says it's a vortex caused by arctic air blowing over relatively warm waters, which causes a tremendous amount of steam. As the air converges, it causes a vortex of steam over the lake. It’s also known as a steam spout.