* WHAT...For the Heat Advisory, heat index values up to 107 expected. For the Extreme Heat Warning, dangerously hot conditions with heat index values up to 111 expected. * WHERE...Portions of west central Arkansas and east central, northeast, and southeast Oklahoma. * WHEN...For the Heat Advisory, until 8 PM CDT this evening. For the Extreme Heat Warning, from noon to 8 PM CDT Tuesday. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Heat related illnesses are possible especially impacting those not acclimated to the conditions or those performing strenuous activities. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Take extra precautions when outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke.