* WHAT...Dangerously hot conditions possible. Afternoon temperatures in the desert valleys will climb into the 108 to 114 degree range, and may exceed 115 along the Colorado River Valley, and 120 Death Valley. * WHERE...Portions of northwest Arizona, southeast California, and southern Nevada including the Greater Mojave Desert region. * WHEN...From Thursday morning through Monday evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat events.