The difference between a regular winter snow storm and a lake effect snow storm are basically the way the storm is fueled and the amount of snow that may ensue. When cold, frigid air travels down from the polar regions, and collides with warmer air, clouds are formed, much like in a thunderstorm, and a snow storm may develop. These clouds, because of the lower temperatures in the winter months, will either produce snow, freezing rain, or sleet, depending on the temperature. The intensity of the snow storm, and the amount of snow that will be deposited, depends on the amount of moisture in the air, temperature, and wind speed. Snow storms may range in strength anywhere from squalls to blizzards, or, in the case of Nor’easters, storms that can produce winds of hurricane strength.
A lake effect snow storm develops much the same way, with a few very important exceptions. These storms head out over large bodies of water such as the Great Lakes, and the cold winds that trail behind them produce the condition known as lake effect snow. As these cold fronts move over the warmer waters below, they are intensified and fueled by the water, and are able to pick up more moisture than would be possible over land. The more moisture that is accumulated, the greater potential for a major snowstorm once it hits land on the leeward side.
Other factors that affect a lake effect snow storm and its intensity are the temperature of the water, how far over the water the storm has to travel, wind direction, and topography of the land on the leeward side.
Storms traveling over warmer water that has not frozen over, will pick up more moisture, and the further the storm has to travel over water, the more moisture it can accumulate. When the temperature difference between the air at 4,900 feet above sea level and the lake is at least 13 degrees C., conditions are right for more heat and moisture to move vertically upward.
The distance that the storm travels, known as fetch, and directional and wind speed shear are both factors that will determine amounts of precipitation, and either cause the storm to stall out, releasing large amounts of snow, or move quickly inland. A change in wind direction, may cause the storm to dissipate before it reaches land. And finally, the topography of the land will determine how far reaching the storm may be. Any elevation in the topography of the land on the leeward side will cause the storm to dump most of its snow upon reaching land, drying out the storm faster.
While any snow storm can be devastating and potentially deadly, when lake effect storms are predicted, there is a fairly good chance that the result will be measured in feet instead of inches.
