An advancing frontal system extending from the Great Lakes region all the way down to the Gulf Coast supported a line of widespread storms and thunderstorms that brought heavy rain to parts of Iowa, Illinois, Missouri, and Indiana. The hardest hit area was northern Illinois where flooding was reported in and around Chicago. The scenario was set up by a deep upper-level trough that moved out of the Rockies and into the Plains. Strong southerly winds ahead of the trough allowed warm, moist air from the Gulf of Mexico to stream northwards all the way up to Lake Michigan. The TRMM-based, near-real

The TRMM satellite flew directly over an intensifying tropical cyclone called Imelda in the South Indian Ocean on April 8, 2013 at 0447 UTC. This rainfall analysis used data collected with TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments. This analysis shows a large area of rainfall on the western side of the developing tropical cyclone. TRMM PR found that some powerful convective storms in this area were dropping rain a rate of over 86mm/hr (~3.4 inches).