Forecast heat index in the eastern United States at 2 p.m. Saturday, from the NAM model. The hottest weather in years is stifling two-thirds of the United States, stretching from Texas and Oklahoma northeastward to Maine. The National Weather Service is using strong language to describe the hazards posed by this event. The Weather Service forecast office in Chicago, for example, is calling this “one of the hotter and more humid air masses since 2012.” By the time this event ends by Tuesday, 86 percent of the Lower 48 states will have experienced high temperatures of at least 90 degrees, and close to 50 percent will have seen temperatures reach or exceed 95 degrees. On Friday morning, forecasters at the Weather Service forecast office in Philadelphia wrote that this heat wave would be “prolonged, dangerous, and potentially deadly.” Warning of a heat index as high as 115 degrees on […]