Authors: Cameron K. Self, Angela E. Crowder, and Matthew D. Eastin
Poster Presentation: 11th Annual AMS Student Conference
Numerous studies of mid-latitude tornadic supercells have demonstrated that the total cell motion is a combination of (a) advection by the mean wind and (b) a motion resulting from the interaction of a convective updraft with the vertically sheared environment (e.g., Bunkers et al. 2000). Several methods to estimate mid-latitude supercell motions from proximity soundings in the nearby environment have been developed (Ramsay and Doswell 2005 provide an overview of many such methods). While such methods have performed well in mid-latitude severe weather environments, several recent studies have used them to estimate cell motions in tropical cyclones without confirming their applicability (Molinari and Vollaro 2008, 2010; Eastin and Link 2009). Interestingly, Eastin and Link showed that the midlatitude methods may not be appropriate for the miniature supercells often observed in tropical cyclones. Their results suggested that an evaluation of the mid-latitude supercell motion methods should be conducted for tropical cyclone cells (tornadic and non-tornadic), and, if needed, a more optimal method for tropical cyclones should be developed.
The goal of this study is to conduct such an evaluation. We employ a database of over 150 “general proximity” soundings associated with tornadic cells in landfalling tropical cyclones from 1997-2008 to compare the mid-latitude estimation methods to observed cell motions. First, observed cell motions (near the time of each tornado report) were determined by the tracking radar reflectivity centroid of each cell in WSR-88D data. Nearby non-tornadic cells were also tracked using similar methods. The convective mode (as defined by Thompson et al. 2010) was also determined for each cell (tornadic and non-tornadic). A synopsis of our preliminary results and their comparison with previous studies will be presented at the conference.