A "mesolow", or small low pressure, formed over western Lake Superior during the early morning hours of January 15th. This low then traveled with the overall wind direction toward the northeast before dissipating during the afternoon hours. The mesolow likely formed due to a land breeze off of Isle Royale. Observations from Isle Royale showed temperatures in the low teens across the island while the adjacent waters were in the mid 30s. This contrast created a boundary oriented along the island, which was enough to create some rotation in the atmosphere.
The animation below is centered on the mesolow. Its counterclockwise rotation is clearly visible as it tracks to the northeast. Other items of note on the image include the ice forming near Thunder Bay, Ontario, and the trailing linear lake effect snow band across southwest Lake Superior (also aided by the convergence of land breezes from Upper Michigan and the Arrowhead of Minnesota).
Note: Because compression of satellite loops greatly degrades the quality, this is an uncompressed 4.5mb file and may take some time to load when using slower connection speeds.