A unique, small-scale, feature was visible on satellite imagery on the afternoon of November 5th across western Lake Superior. Subtle temperature differences between air under dense clouds and air under thin clouds resulted in a small boundary across western Upper Michigan overnight. When this boundary migrated over Lake Superior by late morning, it interacted with weak converging winds off the shores from the Apostle Islands around to western Ontonagon County (first image). The result was a mesoscale low, often shortened as "meso-low" (loop-second image).
Over the Great Lakes, meso-lows are most common in the wintertime near significantly curved lakeshores (e.g. western Lake Superior, southern Lake Michigan). As we head further into winter, keep an eye out for these formations as they are somewhat difficult to predict and can produce quick, but intense bouts of lake effect snow during light winds.
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