york tonight. rob? reporter: good evening, david. the rain from yesterday leaving a lot of humidity in the air. only fueling these thunderstorms. look at this front, stretching from canada all the way to the gulf of mexico. a new flash flood watch up for parts of the southeast. the strongest storms will be tonight across d.c., baltimore and philadelphia. severe thunderstorm watch up there. everything clears out by midnight. but the rain lingers in the southeast. david? rob, thanks so much. when we come back tonight, the 3,200-foot climb in one of america s most famous parks. no rope, no problem. it s america strong. of america s most famous parks. no rope, no problem. it s america strong. ca strong.