The Appalachian Lightning Jump

Cloud-to-ground (CG) lightning flash densities have been consistently lower over the Appalachian Mountains than in surrounding regions, as recorded by the National Lightning Detection Network (NLDN). The decreased lightning activity might be expected as the mountain range can reduce the amount of low level convergence in storms moving through that area. One feature that has not been documented is when CG lightning activity stops completely when a storm system reaches the Appalachians from the west and northwest and begins again as the storm moves beyond the mountains to the east. The occurrences of this lightning jump over the Appalachian Mountains are presented along with some characteristics of the storms exhibiting this behavior.