Observations of Wall Cloud Formation in Supercell Thunderstorms during VORTEX2

This study presents an integrated analysis of dual-Doppler, cloud photogrammetry, surface mobile mesonet, and sounding data to examine wall cloud formation in three supercells observed during the Verification of the Origins of Rotation in Tornadoes Experiment II (VORTEX2). Backward parcel trajectories were calculated from dual-Doppler data for wall clouds that exhibited varying degrees of rotation: significantly rotating and tornadic, weakly rotating, and non-rotating. The non-rotating wall cloud was well displaced from the mesocyclone. For all three wall clouds, much of the observed wall cloud lowering was attributed to evaporatively-cooled parcels in the forward flank region being ingested into the low-level updraft. For the strongly and weakly rotating wall clouds, additional parcels entered wall cloud base from the inflow and rear-flank downdraft. Parcels originating in the rear-flank downdraft descended into the wall cloud. For the strongly rotating wall cloud, additional localized wall cloud lowering near the circulation center was created by the adiabatic cooling associated with the greater than 10 hPa pressure deficit. The observational results presented herein will be compared to long-standing wall cloud formation conceptual models published in the refereed literature