* WHAT. Heat index values up to 105 degrees. * WHERE. In Arkansas, Lee AR and Phillips Counties. In Mississippi, Coahoma, Quitman, Tallahatchie, and Tunica Counties. * WHEN. Until 8 PM CDT this evening. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

* WHAT. Heat index values up to 108 degrees expected. * WHERE. Portions of East Arkansas, North Mississippi, Southeast Missouri, and West Tennessee. * WHEN. From 11 AM to 8 PM CDT Saturday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

* WHAT. For the Heat Advisory, heat index values up to 106 degrees. For the Excessive Heat Warning, dangerously hot conditions with heat index values up to 112 degrees expected. * WHERE. In Arkansas, Lee AR and Phillips Counties. In Mississippi, Coahoma, Quitman, Tallahatchie, and Tunica Counties. * WHEN. For the Heat Advisory, until 8 PM CDT this evening. For the Excessive Heat Warning, from 11 AM to 8 PM CDT Saturday. * IMPACTS. Heat related illnesses increase significantly during extreme heat and high humidity events.

* WHAT. Dangerously hot conditions with heat index values up to 111 degrees expected. * WHERE. In Arkansas, Clay, Craighead, Cross, Greene, Poinsett, and St. Francis Counties. In Mississippi, Panola County. * WHEN. From 11 AM to 8 PM CDT Saturday. * IMPACTS. Heat related illnesses increase significantly during extreme heat and high humidity events.