As a center of low pressure moves east from southern Lake Michigan across southern Lower Michigan, an associated cold front will swing south and east through the Chicago area this Sunday afternoon.
Westerly winds will shift to the north-northeast and strengthen, eventually gusting at times over 35 mph, especially along the Lake Michigan shoreline where wind-driven 5 to 8-ft waves along the Illinois shoreline from Evanston to the Indiana state line and 8 to 13-ft waves along the Indiana shoreline will once again cause lakeshore flooding (a lakeshore flood Advisory in NW Indiana is depicted in green on the headlined map).
Very cold temperatures aloft will trigger scattered instability showers, that may have graupel or wet snow mixed in at times. As the low pressure system moves farther east, winds will diminish and showers end from the west later tonight with skies becoming partly cloudy by morning.
With another surge of cold air spreading over our area, the partially-clearing skies and lighter winds later tonight may allow temperatures to drop into the lower 30s especially west and north of Chicago with possible scattered frost early Monday morning.
Rainfall amounts will have little impact on area rivers and streams that will continue a slow fall with Minor flooding continuing at Harvard on the Fox River and from Starved Rock to LaSalle on the Illinois River.