A well-defined easterly lake breeze has intersected west winds and produced enough surface convergence to build a line of slow-moving thunderstorms. Cook county will be under a Flash Flood Warning until 7:45pm due to the torrential downpours fed by this tropical air mass. The storms are pulse type, meaning they will flare up then die off rather rapidly over any one area. Watch out for standing water and the potential for damaging winds with these cells.
Mike
