The authors thank Casey Letkewicz, Matt Morin, and Johannes Dahl of the Convective Storms Group at North Carolina State University for helpful comments and assistance throughout the course of this project. Drs. Sandra Yuter, Gary Lackmann, and Anantha Aiyyer also provided valuable feedback throughout the course of this work as part of the first author’s doctoral dissertation committee. Additionally, the insightful comments from two anonymous reviewers greatly enhanced this manuscript. Computational resources and data storage were provided by the Office of Information Technology High Performance Computing at North Carolina State University. We would also like to thank the developers of the WDSS-II software for maintaining and providing this software free of charge for research purposes. This research was supported by NSF Grants ATM-0552154 and ATM-0758509.
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For the sake of simplicity, we will assume an eastward-moving squall line oriented north–south, as shown in the schematic in Fig. 7.
Only reports the occurred within 50 km of the portion of the squall line eventually involved in the merger were counted, as in some cases the squall line extended for 10s or 100s of kilometers away from the merger location. This was done subjectively using radar animations to track the section of the squall line eventually involved in the merger backward in time and, generally, was restricted to the time period where the merging supercell was also present.