An empirical relationship between radar reflectivity levels exceeding 32 and 40 dBZ at a height of 6 km and sferics data is used to generate maps that indicate regions of thunderstorms. These radar maps serve as ground truth when compared with colocated GOES visible and infrared imagery. A threshold computed to equalize the radar and satellite thunderstorm areas delineates in visible-IR space that is most probably associated with electrical activity. The locations of satellite-delineated storms beyond radar range, on the synoptic scale, show good agreement with sources of lightning determined from sferics detectors. The skill of the extrapolation of these areas for short-range forecasting is discussed.