Analysis of Tornadogenesis Failure Using Rapid-Scan Data from the Atmospheric Imaging Radar

Tornadogenesis in supercell thunderstorms has been a heavily studied topic by the atmospheric science

community for several decades. However, the reasons why some supercells produce tornadoes, while others

in similar environments and with similar characteristics do not, remains poorly understood. For this study,

tornadogenesis failure is defined as a supercell appearing capable of tornado production, both visually and

by meeting a vertically contiguous differential velocity (ΔV) threshold, without producing a sustained tornado.

Data from a supercell that appeared capable of tornadogenesis (but which failed to produce a sustained

tornado) was collected by the Atmospheric Imaging Radar (the AIR, a high temporal resolution radar) near

Denver, CO on 21 May 2014. These data were examined to explore the mechanisms of tornadogenesis failure

within supercell thunderstorms. Analysis was performed on the rear-flank downdraft (RFD) region and

mesocyclone, as previous work highlights the importance of these supercell features in tornadogenesis. Preliminary

results have found a lack of vertical continuity in rotation between the lowest level of data analyzed

(100 m AGL), and heights aloft (> 500 m AGL). A relative maximum in DV occurred approximately 100 m

AGL (0.5° in elevation on the radar) around the time of suspected tornadogenesis failure; this contrasts with

weaker ΔV at elevations aloft. Additionally, the RFD produced by the Denver Supercell had a peak in intensity

aloft (between 2.5 and 3 km in height) just prior to the time of tornadogenesis failure, while simultaneously

experiencing a relative minimum in intensity in the layer between the ground and 1 km.