Key keywords: extreme heat warning, dangerous summer heat, Friday to Saturday severe storms, heat-related illness prevention, thunderstorm wind gust risk, flash flood watch, national weather service alert, weekend weather disruption The National Weather Service (NWS) has issued widespread extreme heat advisories and excessive heat warnings across 28 U.S. states on Thursday, as a persistent dome of high pressure pushes daytime high temperatures 15 to 20 degrees above seasonal averages for most of the Midwest, Northeast, and Southern Plains. Millions of residents are facing dangerous heat conditions, with afternoon heat index values reaching between 105°F and 118°F in most populated areas, putting vulnerable groups including elderly people, young children, pregnant individuals, and those with chronic health conditions at severe risk of heat exhaustion, heat stroke, and other heat-related illnesses. Local health departments have opened 327 cooling centers across affected regions, and are urging residents to avoid outdoor activities between 10 a.m. and 6 p.m., drink at least 8 ounces of water every hour, and never leave children, pets, or vulnerable adults unattended in parked vehicles, even for a minute. As of 2 p.m. ET Thursday, local emergency response teams have reported 79 confirmed heat-related hospitalizations across 11 states, with 3 fatalities linked to the ongoing heat event in Texas and Oklahoma. While the heat dome is expected to break late Thursday night as a cold front pushes east from the Rocky Mountains, the clash between the cold, dry air mass and the lingering warm, moist air trapped by the heat dome will trigger a widespread severe weather event starting Friday midday across the Upper Midwest, and expanding to the Northeast and Mid-Atlantic regions by Friday evening, lasting through Saturday afternoon. The NWS has categorized the storm risk as Level 3 out of 5 for most of Iowa, Illinois, Indiana, and Ohio, with the threat of 70+ mph wind gusts, golf-ball sized hail, isolated tornadoes, and short-duration heavy rainfall that could reach 2 to 3 inches per hour in some areas, leading to significant flash flood risks for low-lying, urban, and poor drainage areas. Residents planning outdoor weekend activities including music festivals, farmers markets, camping trips, and sports competitions are advised to monitor local weather alerts closely, adjust event plans if possible, and prepare emergency kits with water, non-perishable food, flashlights, and first-aid supplies in case of power outages or travel disruptions. Meteorologists note that the storm system is moving at an average speed of 35 mph, so weather conditions can deteriorate very quickly with little advance warning in some locations.