The influence of storm motion on the azimuthal distribution of electrified convection in 35 Atlantic basin tropical cyclones from 1985-1999 was examined using data from the National Lightning Detection Network. Flashes in the inner 100 km most often occurred in front of the storms, with a preference for the right front quadrant, while flashes in the rainbands showed a strong right to left asymmetry with a strong preference for the right front quadrant. These results are consistent with the extensive findings of both numerical and observational studies that have examined asymmetries in rainfall, reflectivity and vertical motion with respect to storm motion.

The storm motion signature was compared to the effects of vertical wind shear on convective asymmetries to determine which effect was dominant. In time periods where there was no overlap of the separate signals, the vertical wind shear signature was seen to dominate the distribution of convection, as the motion signal all but disappeared. It is hypothesized that in time periods with vertical shear greater than 5 m/s that the shear is the main influence on the distribution of convection and the motion signature may simply be a reflection of the strong shear signature.

Nonetheless, since vertical shear and storm motion both influence the distribution of convection in tropical cyclones, they themselves must be related. In 78% of the time periods examined, storm motion was to the left of (counterclockwise from) the vertical wind shear vector, with 50% of the time periods having a storm motion within 90 degrees to the left of the shear vector. These results support the theory of an upright cyclonic vortex with a broad anticyclone advected downshear of the low level center and inducing storm motion to the left of the local wind shear vector.