* WHAT...For the first Heat Advisory, heat index values up to 107. For the second Heat Advisory, heat index values up to 107 expected. * WHERE...Portions of east central, southeast, southern, and southwest Oklahoma and northern Texas. * WHEN...For the first Heat Advisory, until 8 PM CDT this evening. For the second Heat Advisory, from noon to 8 PM CDT Saturday. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses.