James Aanstoos, Department of Geological and Atmospheric Sciences, Iowa State University


On May 20th, 2013, Mother Nature unleashed its wrath on Oklahoma City, Newcastle, and Moore, Oklahoma with a violent and long-track EF-5 tornado. The University of Oklahoma (OU) was prepared with their Advanced Radar Research Center’s PX-1000 transportable, polarimetric, X-band weather radar (Kurdzo et al. 2015). The PX-1000 took twenty second scans of this storm at a high resolution with its only limitation of keeping the beam at a fixed elevation of 2.6°, below 500m, to achieve the fastest scan times possible. The radar observed a number of small scale features that are typically found in a tornado producing cyclic supercell. This includes eight rear flank gust front surges, six debris ejections and multiple shifts in path. The rear flank down draft is one of the key components in tightening a supercell’s circulation and inducing tornadogenesis. With this in mind, is it possible that surges in the rear flank down draft could influence some of the characteristics of the tornado? We will investigate this question throughout this paper, specifically, do rear flank gust front surges (RFGFS) have any influence on the differential velocity, speed, or direction of the tornado? During our investigation we also stumbled upon some data that suggests that the RFGFS could have also influenced the damage intensity and spread in some regions. This will be discussed in a supplemental material section on page 18.

Copyright Owner

Jacob W. Smith


Included in

Meteorology Commons