Forecasters warned people celebrating Father’s Day outdoors to take precautions as triple-digit temperatures prompted heat advisories across much of the southern U.S. The unstable conditions triggered thunderstorms that knocked out power from Oklahoma to Mississippi. It's also producing gusty winds in the Southwest that raised wildfire threats in Arizona and New Mexico. A suspected tornado struck near Scranton, Arkansas early Sunday, toppling trees onto homes. There were no immediate reports of serious injuries. Reports indicated more than 740,000 people are without power in Oklahoma, Texas, Louisiana, Arkansas, and Mississippi.
