* WHAT. Flash flooding caused by excessive rainfall is possible. * WHERE. Portions of north central and northeast Illinois, including the following areas, in north central Illinois, Boone, De Kalb, Lee, Ogle and Winnebago. In northeast Illinois, Central Cook, DuPage, Kane, Kendall, Lake IL, McHenry, Northern Cook, Northern Will and Southern Cook. * WHEN. Through Friday morning. * IMPACTS. Creeks and streams may rise out of their banks. Flooding may occur in poor drainage and urban areas. Underpasses may be flooded. Roads and streets may be flooded. * ADDITIONAL DETAILS. - Repeated waves of thunderstorms producing very heavy rainfall are expected across northern Illinois tonight. Given the very moist air mass in place, the most intense thunderstorms will be capable of producing 2 or more inches of rain in an hour. Some portions of the watch area currently receiving very heavy rainfall will likely experience additional waves of storms tonight, thus increasing the threat of flash flooding. - http://www.weather.gov/safety/flood
