Rapid ice cover development over the eastern Great Lakes in late January 2019

An Arctic outbreak occurred in late January 2019 over the Great Lakes which caused not only lake-effect snowfall but a rapid increase in ice coverage across the lakes, particularly over shallower lakes.

First, we’ll look at GOES-16 imagery prior to the Arctic outbreak. GOES-16 GeoColor imagery on January 25 (click to open a larger window):

The clouds associated with lake-effect snowbands show up well, however ice cover on the lake can be difficult to see since the white colored ice may blend in with clouds of the same color. In order to help make the discrimination between ice cover and clouds, the CIRA Snow/Cloud Layers product can be viewed (click to open a larger window):

In the product, low/water clouds generally appear as yellow or possibly greenish while high/ice clouds appear as magenta. Snow on the ground will appear white. Ice cover on the lakes appear white or bluish/white.

Next, we’ll analyze the same imagery after the Arctic outbreak across the Great Lakes. First, the GeoColor product (click to open a larger window):

and the CIRA Snow/Cloud Layers product (click to open a larger window):

Compare this loop with the same loop observed on January 25 and you can readily see the increase in ice coverage across the Great Lakes, in particular over Lake Erie. Lake Erie is the most shallow of the Great Lakes making it quicker to develop ice cover and in fact lake surface temperatures on January 25 were near freezing. Ice cover significantly reduces sensible/latent heat fluxes which helps explain why there is a lack of lake-effect clouds across Lake Erie on the February 1 imagery. Finally, a mesovortex is observed over Lake Michigan moving northward.

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