When the phrase, 'lake-effect' is uttered, images of blinding snow squalls in the depths of an arctic siege typically come to mind. These convective storms, sustained by the heat and moisture fluxes from unfrozen lake waters, are what first elicited the intellectual curiosity of Great Lake atmospheric researchers and forecasters some 50 years past.
Climatological data suggest otherwise.
An analysis of local precipitation climatologies downwind of the eastern Lakes indicate that lake enhancement occurs well before the season's first snow. In fact, early season cold-air outbreaks over the much warmer Great Lakes can produce substantial rains, occasionally enough to cause flooding. Seven years of autumnal precipitation data were examined to determine the characteristics of lake-effect precipitation downwind of Lake Erie. As might be expected, the mean atmospheric conditions during rain events were similar to the conditions during lake-effect snow events. This was particularly true with regard to the overall positions of transient synoptic features.