NEW : Heat exhaustion kills man in heat . The longer the heat wave lasts , the greater the dangers , meteorologist says . Severe storms are expected Friday in the Midwest , Saturday in the Northeast . Heat waves are expected to hit 105 in some areas Thursday .
NEW : Heat exhaustion kills man in Kentucky . The longer the heat wave lasts , the greater the dangers , meteorologist says . Severe storms are expected Friday in the Midwest , Saturday in the Northeast . Heat indexes are expected to hit 105 in some cities Thursday .