* WHAT...Heat index values between 100 and 107 for at least three successive days. Limited nighttime relief as low temperatures are only expected to fall into the low-to-mid 70s. * WHERE...Portions of south central Indiana and north central, northwest, and south central Kentucky. * WHEN...Until 8 PM EDT /7 PM CDT/ Friday. * IMPACTS...Prolonged hot temperatures and high humidity may cause heat illnesses.