In mid latitudes like yours there is a phenomenon called a 'seische' (SIC, but there are variations).
It's caused by extreme atmospheric pressure differences in short distances--usually low pressure systems where isobars are very close on a map. The atmospheric pressure can seem to press down on lakes both big and small causing what would appear to be a heavy high tide. Caused mostly by high winds, this rare event has amazing low cloud formations that are indeed beautiful but at the same time very deadly to swimmers and small craft on the Chain -O-Lakes as well as the Great Lakes.
Lake Michigan, Huron, and Superior are known to have this phenomenon, although rarely, in Spring and summer.
