* WHAT...For both Heat Advisories, heat index values in excess of 105F degrees expected. * WHERE...Portions of northeast Louisiana and central, east central, south central, southeast, southwest, and west central Mississippi. * WHEN...For the both Heat Advisories, until 9 PM CDT this evening and from 10 AM to 9 PM CDT Monday. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses.