WINONA, Minn. — A cold front approaching from the west was expected to generate severe weather in southeast Minnesota and adjacent areas this evening. Thunderstorms were forecast until around midnight, possibly with large hail and damaging winds and maybe tornadoes.  Downpours may drop an inch of rain, the National Weather Service said.  Cooler, drier air will move in behind the cold front on Friday. For Labor Day weekend, expect sunny skies and highs and  the upper 70s.