he National Weather Service in Chicago has issued a * Special Marine Warning for... Nearshore Waters from Winthrop Harbor to Calumet Harbor... Nearshore Waters from Calumet Harbor to Gary... Open Waters from Winthrop Harbor to Michigan City out to Mid Lake... * Until 730 PM CDT. * At 435 PM CDT, severe thunderstorms capable of producing waterspouts were located along a line extending from 8 nm west of Ohare Airport to 10 nm east of Aurora to near Joliet, moving northeast at 30 knots. HAZARD...Waterspouts, wind gusts in excess of 50 knots, and small hail. SOURCE...Trained Weather Spotters. This line of storms has a history of producing wind gusts over 50 knots. IMPACT...Waterspouts can easily overturn boats and create locally hazardous seas. Boats could suffer significant structural damage in high winds. Small craft could capsize in suddenly higher waves. * Locations impacted include... Harrison-Dever Crib, Wilmette Harbor, 31st Street Harbor, Monroe Harbor, Calumet Harbor, Winthrop Harbor, Indiana Harbor, Montrose Harbor, Waukegan Harbor, Burnham Harbor, Hammond Marina and Jackson Park Harbor. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Tornado Watch remains in effect until 800 PM CDT for northeastern Illinois.