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Investigating the Role of Wave-like Reflectivity Segments during the 17 November 2013 EF-4 Washington, Illinois Tornado

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Wednesday, 5 November 2014
Capitol Ballroom AB (Madison Concourse Hotel)
Edward J. Shimon III, NOAA/NWS Forecast Office, Lincoln, IL
Manuscript (1.3 MB)

Handout (1.6 MB)

Tornadogenesis has been a focus of study for decades. In general, the conditions and ingredients needed for tornadogenesis are known, but determining when they will co-exist in the atmosphere can still be a difficult task. Recent investigation into one ingredient has been a focus on wave-like reflectivity segments (WRS), presumably caused by gravity waves. Recognizing their existence in the near-storm environment remains a challenging task, but research has confirmed that they can play a significant role in tornadogenesis or the development of damaging downburst winds. On 17 November 2013, two WRSs were observed on the KILX WSR-88D radar propagating through the Illinois River Valley during the late morning hours. Interactions between the first WRS and an intense convective core appear to have been associated with increases in mesocyclone circulation and subsequent tornadogenesis. The second WRS appeared to be associated with an abrupt and significant intensification of the tornado mesocyclone, as damage levels reached EF-4 on the enhanced Fujita scale and the tornado diameter expanded to nearly a half-mile wide. The interaction was observed on the KILX radar during post-event analysis. This study will focus on the details of the WRS detection, propagation, and role in the tornadic event that devastated the community of Washington, Illinois. The findings will hopefully aid forecasters with techniques and examples of WRSs that will allow for improved situational awareness in real-time during the next tornadic event. The intended purpose of the study is for increased tornado warning lead time and subsequent reduction of injuries and loss of life during tornadic events where WRSs play a role.