* WHAT...Flash Flooding caused by excessive rainfall continues to be possible. * WHERE...Portions of southwest Illinois, including the following areas, Madison IL, Monroe IL and Saint Clair IL and east central Missouri, including the following areas, Jefferson MO, Lincoln MO, Saint Charles MO, Saint Louis City MO and Saint Louis MO. * WHEN...Through Tuesday afternoon. * IMPACTS...Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. * ADDITIONAL DETAILS... - Potential rainfall amounts of 2 to 4 inches, with localized higher amounts of 4 to 6 inches.