Mesoscale Convective System
An area of strong convective activity that develops into a separate surface low/ frontal system. One is currently observed to be forming in Illinois, centered just north of Peoria. What's really cool about it is that all the major features (fronts, the low pressure center) are currently observable on radar. The system is moving towards Chicago, so expect heavy rain and some thunder in the next few hours.

ESA(20030404.1)