Multiple rounds of locally heavy rain with the risk for flash flooding,as well as severe thunderstorms, expected in the north-central U.S....Late-season wet snow for the northern Rockies beginning on Monday....A heat wave will quickly spread from the Plains Sunday into the GreatLakes/Upper Ohio Valley on MondayA plume of tropical moisture will bring the threat for heavy downpoursand flash flooding to the central Gulf Coast...Some severe storms will be possible Saturday evening ahea...