Wednesday, 5 November 2014
Capitol Ballroom AB (Madison Concourse Hotel)
Mobile radar observations of a nontornadic supercell obtained by two Doppler on Wheels (DOW) radars on 6 June 2010 near Ogallala, NE, during the Verification of the Origins of Rotation in Tornadoes Experiment 2 (VORTEX2) are presented. A dual-Doppler wind synthesis from the beginning of the radar observation period depicts the three-dimensional wind field near the storm, including a region of inflow southeast of the cell, the updraft, rear-flank downdraft, and low-level mesoscyclone. The surface mesocyclone was only about 1.2 km deep and was not collocated with the strongest circulation at 1 km above ground level. Photographs of tornadogenesis failure are also presented and depict a surge of northerly outflow undercutting this circulation just prior to the beginning of radar observations. Later in the observation period, Doppler radar data reveal that this surge of outflow displaced the rear-flank gust front several kilometers southeast of the low-level mesocyclone and updraft. An analysis of in-situ thermodynamic data collected by instrumented mobile mesonet vehicles within the outflow reveals it to be potentially cold, with virtual potential temperature deficits in excess of 6 K. The low-level mesocyclone was thus located in a region of cold, divergent outflow which prevented it from strengthening. This likely resulted in the eventual demise of the low-level circulation and, later, the midlevel updraft associated with this supercell.
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