The amazing "Firefall" at Yosemite National Park is set to return on Thursday, when Mother Nature makes it look like lava is flowing off a cliff. Unfortunately, it requires near perfect conditions and the view changes day to day. There has to be enough water flowing, and the light has to be just right. If it's cloudy outside, the glow can't happen, so here's hoping our February weather is favorable. Last year was one of the best years for viewing. This year, expect the period for potential Firefall sightings to be between February 13 and 27.