Flash flood warnings and watches were in effect Wednesday across much of the Mid-Atlantic and deep into upstate New York as heavy rains continued to pound the waterlogged region for a fifth day.  About 30 million people have been under a cloud of flood watches for days, most of them in the East, as almost a quarter of the nation struggled with a double whammy of overwhelming waters or excessive heat.  Almost 40 million people from Washington state to Arizona were dealing with a dangerous heat wave, the National Weather Service said.  In the East, weather service radar showed bands of moderate to heavy rainfall with embedded thunderstorms extending from eastern North Carolina across Virginia and into Maryland, central Pennsylvania and central and western New York stat