..EXCESSIVE HEAT WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH SATURDAY EVENING... The National Weather Service in Saint Louis has issued an Excessive Heat Watch, which is in effect from Wednesday afternoon through Saturday evening. * TIMING...Tuesday afternoon through Friday evening. * HEAT INDEX VALUES...Between 105 and 110 each afternoon and early evening. * IMPACTS...The combination of hot temperatures and high humidity will lead to an increased risk of heat-related stress and illness. The very young, the elderly, those without air conditioning, and those participating in strenuous outdoor activities will be the most susceptible. Also, car interiors can reach lethal temperatures in a matter of minutes. PRECAUTIONARY/PREPAREDNESS ACTIONS... An Excessive Heat Watch is advanced notice that there is the potential for a prolonged period of hot temperatures and high humidity. This will create a dangerous situation in which heat- related illnesses are more likely. Begin making preparations now, by making sure your air conditioning is in good working order or know where to go to stay cool.