* WHAT...Heat index values up to 110 degrees. * WHERE...Portions of central and south Mississippi, southeast Arkansas, and northeast Louisiana. * WHEN...Until 8 PM CDT Monday. * IMPACTS...High temperatures and high humidity may cause heat related illnesses. * ADDITIONAL DETAILS...Temperatures at night will not bring much relief as they struggle to fall below 80 in some cases. The threat for dangerous heat will continue into next week.