A nasty collision of heat and humidity is expected to broil the South beginning this weekend and sweeping into the upcoming week. Heat indexes over 100 degrees are possible in Houston; Oklahoma City and Tulsa, Oklahoma; Little Rock, Arkansas; Memphis and Nashville, Tennessee, St. Louis and Kansas City, Missouri; Jackson and Tupelo, Mississippi; and Huntsville, Alabama. Heat illnesses, including heat exhaustion and heat stroke, are more likely in these conditions. Take it easy and stay indoors when you can.