Weather Alert...HEAT ADVISORY NOW IN EFFECT UNTIL 8 PM CDT FRIDAY... * WHAT...Maximum heat index values of 105 to 110 expected each afternoon, with low temperatures only falling into the upper 70s in most areas. * WHERE...Portions of central, east central, northern, northwest, southeast, southern, southwest, and western Oklahoma and northern Texas. * WHEN...Until 8 PM CDT Friday. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.