Authorities in California and Nevada have issued mandatory evacuation orders for tens of thousands of people as an intense heat wave grips large swaths of the Southwest. Fast-moving wildfires are burning south of Reno in Nevada and in California’s San Bernardino County, Orange County, at the foothills of L.A.'s Angeles National Forest, as well as in Northern California's Lake County. UCLA climate scientist Daniel Swain said “extreme fire behavior” has also been observed in Oregon, Idaho and Wyoming.