What is lake-effect snow? Growing up in the south Chicago suburbs, we would occasionally see this phenomenon although I was more likely to hear the local T.V. weather folk talk about it for areas of northwestern Indiana.
The simplest explanation is that when cold and dry air blows over warmer lake water, the air is both warmed and moistened. This combination in the lowest levels of the atmosphere leads to a more unstable condition.
This time of year is prime for lake effect snow because water temperatures cool at a slower pace than the land and air cold enough to support snow is more likely to be dragged in behind a more active storm system pattern.
Water vs. Land Temperature
There are other factors too. The proper wind field is important. A bigger lake-effect snow will occur when the fetch or distance the air blows over the lake is maximized. One very notoreous set-up is a WSW wind blowing essentially over the length of Lake Erie which then sets up heavy snows on the eastern end, most often reported when it targets the city of Buffalo, NY!
The winds in the lowest layers must also be set up to encourage air to rise. Other factors include topography, friction and temperature difference.
A great wind fetch for dumping on Buffalo!
North Winds Producing Lake-Effect Snow on Radar
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