On Tornadogenesis in Two Supercells in Oklahoma in the Spring of 2019 as Documented by a Rapid-Scan, X-band, Polarimetric, Mobile Doppler Radar (RaXPol)

During our 2019 spring field program the rapid-scan, X-band, polarimetric, mobile Doppler radar (RaXPol) documented tornadogenesis in two supercells: early in the program, on 1 May, in south-central Oklahoma and at the end of the program, on 15 June, in western Oklahoma. In both cases the storm-intercept crews had difficulty seeing the tornado: In the first, the storm was viewed from the west, so the tornado was hidden by precipitation; in the second, the tornado occurred after dark and was visible only when lightning afforded a silhouetted view. The behavior of the single Doppler vortex signature as a function of height and time will be discussed and compared with similar tornadogenesis analyses from other storms previously documented. The focus is on whether tornadogenesis was initiated aloft and built downward or was initiated near the surface and built upward. In a majority of previous fine-scale analyses, tornadogenesis was initiated near the surface following vortex formation aloft, and built upward. Other aspects of storm features in the reflectivity and polarimetric-variable fields such as debris signatures and weak-echo holes, contemporaneous with tornadogenesis, and cyclic mesocyclogenesis will also be discussed.