National Weather Service Chicago/Romeoville IL
8:46 AM Saturday March 17.
waves are provided as a range of significant wave heights, which is the average of the highest 1/3 of the wave, along with the average height of the highest 10% of the waves which will occasionally be encountered. synopsis, low pressure of 29.8 inches over southern illinois this morning, will move to the carolinas by this evening while weakening to 29.8 inches. high pressure of 30.1 inches will build over the upper midwest tonight while weak low pressure of 29.9 inches drops southeast over the central great lakes late tonight into sunday morning. for monday into early tuesday, lake michigan will find itself between high pressure of 30.5 inches across ontario and low pressure of 29.5 inches moving eastward into the ohio valley.