Severe storms threaten to bring rain, hail and high winds to parts of northern Illinois and northwest Indiana on Memorial Day. An area of showers and thunderstorms is likely to travel across north central Illinois to northwest Indiana around the afternoon, according to the National Weather Service. The threat of severe weather is low during the late morning hours but is expected to increase from 3 p.m. to 9 p.m., the weather service said. Storms may bring winds up to 70 mph and half-dollar sized hail to the Chicago area. A few tornadoes are possible for the areas around Rockford, Ottowa, Aurora, Joliet and Watseka, the weather service said. Heavy rainfall is likely to accompany the storms which may result in flash flooding in some areas, the weather service said.