This paper will present detailed radar and damage survey analyses in an attempt to illustrate the structural relationship between the damage swath and bow echo, as observed by the St. Louis WSR-88D. It will be shown that the primary damage swath of straight-line wind damage was not created by a descending rear-inflow jet at the apex of the bow echo. Rather, it was created by an intense, low-level mesovortex north of the bow echo apex. Observations of mesovortices within bow echoes creating long swaths of straight-line wind damage are not well-documented in the literature.
Detailed analyses of 11 low-level mesovortices formed on the leading edge of the convective system will also be presented. In particular, it will be shown that it is possible to distinguish between tornadic and non-tornadic mesovortices. Specifically, the tornadic vortices are stronger (below 3 km AGL) and longer lived than their non tornadic counterparts. Tornadic vortices consistently strengthen dramatically at low levels and deepen rapidly prior to tornadogenesis. Similar evolution is not observed with the non tornadic vortices. The average time from vortex genesis to tornado genesis was about 12 minutes. The forecasting implications of these findings will be discussed.