This study addresses winter season lightning by examining synoptic-scale ci
rculations, cloud-to-ground (CG) lightning patterns, and frozen precipitati
on. Specifically, locations, frequencies, and polarities of CG flashes are
related to the location, intensity, and type of heavy frozen precipitation
(snow, freezing rain, or ice pellets) for seven winter storms affecting the
southeast United States from 1994 through 1997. The results suggest two di
stinct phases of winter storm development, each producing different pattern
s of CG lightning and frozen precipitation. These phases are termed the arc
tic front (AF) and migratory cyclone (MC) types.
Analysis was performed on 27 periods within the seven cases. In several per
iods, there were significant numbers of CG flashes within or near a subfree
zing surface air mass and frozen precipitation when a quasistationary arcti
c front existed. These periods were classified as AF phases. This flash pat
tern indicates a connection between the intensity of convection (associated
with CG flashes) and downwind frozen precipitation. In these situations th
ere was strong southwesterly flow aloft, which may have advected ice partic
les from these convective clouds into stratiform clouds near the frontal su
rface. This process resembles the "seeder-feeder'' mechanism of precipitati
on growth.
The AF phases eventually developed into MC phases, and the latter were more
common in this study. The MC phases in general exhibit a different spatial
relationship between CG lightning and heavy frozen precipitation; that is,
CG flashes retreat toward the warm sector of the cyclone and thus are not
proximal to the 0 degreesC surface isotherm. There appears to be little con
nection between convection and frozen precipitation in most of these situat
ions. The distinction between AF and MC phases, in conjunction with CG ligh
tning monitoring, may aid forecasts of the duration and amount of frozen pr
ecipitation during winter storms.