What we have here is surface vorticity (rising, denoted by color fills) and surface convergence/divergence (red and black, respectively). Convergence is associated with air converging on a point to make storms in the summer, and intense snow in the winter. We are seeing some convergence activity occurring on Lake Michigan westward into Chicago, where surface vorticity is also higher, suggesting that snowfall may become enhanced in those areas. We expect the lake enhancement to eventually turn to Michigan and dump snow on those areas. More updates as they come.