Dangerous heatwave to impact much of the West, while oppressive heatand humidity also swelter areas from the Southern Plains to theMid-Atlantic......Flash flooding and severe thunderstorms possible over the next few daysacross portions of the Plains, Midwest, and Ohio Valley...Record-breaking and dangerous heat is forecast to make this Fourth of Julyweek a scorcher across much of the West and from the southern Plains tothe Mid-Atlantic. Nearly 150 million residents are currently underheat-rel...