Monday, 10 January 2005: 11:30 AM
An analysis of lightning holes in a DFW supercell storm using total lightning and radar information
Lightning holes have been observed on several occasions in severe storms using three-dimensional total lightning mapping information. They have been found in the cores of severe storms and have been implicitly associated with very strong updrafts in the storm (>50 m/s). By implication, this means that they are associated with bounded weak echo regions as observed by radar. The automatic identification of lightning holes presumably would serve to identify storms capable of producing severe weather with a lead time on the order of the time between when a strong updraft reaches maturity and when the by-products reach ground level. However, in looking at high-resolution total lightning information, one can often identify features that look like lightning holes but are not. Therefore, the temporal and spatial resolution of the data representation is critical for proper identification of holes. Another critical component to identifying holes is to search only within storm cores rather than developing stratiform regions or anvils that have lightning activity. Thus, the objectives of this paper are three-fold. First, we use radar information to demonstrate that lightning holes observed in a severe hailstorm near Dallas-Ft Worth, Texas, were in fact associated with bounded weak echo regions as observed by the Ft. Worth NEXRAD radar. Then, we show that the locations where lightning flashes originate can be used to distinguish the storm cores from attached anvils that have lightning activity that sometimes exhibits hole-like features. Finally, we represent the lightning activity in a couple of ways with different spatial resolutions to demonstrate the degree of resolution necessary for the proper identification of the true lightning holes.