CHICAGO -- The Chicago National Weather Service Forecast Office has issued a Flash Flood Watch for the entire Chicago area starting at 1 a.m. Monday and continuing until 1 a.m. Tuesday (late Sunday night until late Monday night).
Two rounds of potentially severe thunderstorms that could in addition produce flash-flood-producing significant rainfalls of one to three inches (locally higher amounts possible) are expected to occur. The first round could begin later Sunday night and continue into Monday. The second round of strong to severe storms could spread over our area later Monday afternoon into the overnight hours.
A very moist unstable air mass will be in place through Monday night with dew points in the mid to upper 70s, allowing any thunderstorms that develop to produce torrential flooding rainfall.