170 Effects of Precipitation "Bursts" on Supercell Dynamics in Idealized Simulations

Thursday, 25 October 2018
Stowe & Atrium rooms (Stoweflake Mountain Resort )
Scott Loeffler, Pennsylvania State Univ., University Park, PA; and M. R. Kumjian and P. Markowski

Past studies and anecdotal observations from the operational community have noted interactions between supercell storms and additional precipitation sources, including storm mergers, secondary storms in close proximity to the primary supercell, and descending reflectivity cores. Some of these studies speculated that this additional precipitation and associated negative buoyancy affect supercell dynamics, even enhancing the magnitude of the low-level vertical vorticity maximum and, in some cases, triggering tornadogenesis. In this study, we use idealized simulations to help elucidate any microphysical effects that these additional precipitation sources have on supercell dynamics. After simulating a supercell (control run), we introduce a precipitation “burst” at a given time and location and re-run the simulation forward from that point, analyzing the differences between these simulations and the control run. The horizontal location of the precipitation burst is varied within and around the supercell to assess whether any effects are location dependent, as suggested by previous work using dry simulations. In addition to burst location, the burst composition is also varied by altering median drop size (and thus differential reflectivity ZDR) while keeping the radar reflectivity factor (ZH) the same. Preliminary results show shifts in the location and intensity of the main updraft and rear-flank gust front in relation to the low-level vertical vorticity maximum.
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