Fetch is the distance wind travels over the warm lake. The longer the fetch, the more moisture for the development of heavier lake effect snow. The shape of three of the five Great Lakes are long and narrow so these lakes have long fetches. A small shift in the wind direction can change the location and the potential intensity of the snow. Look at the examples below for areas along the lakes that would be impacted by lake effect snow.
A northwest wind (320°) travels almost 130 miles across Lake Superior, 150 miles across Lake Huron, but only about 60 miles across Lake Erie.
A west-southwest wind (250°) travels 30 miles across Lake Michigan, 60 miles across Lake Huron, and 130 miles across Lake Erie.