An Examination of Convective Enhancement within Complex Terrain on 5 April 2017 during VORTEX-SE

The third intensive observing period (IOP) during year 2 of the Verification of the Origins of Rotation in Tornadoes Experiment – Southeast (VORTEX-SE) on 5 April 2017 featured an environment that at first glance should have been supportive of organized deep convection with the possibility of tornadoes. However, convection within the VORTEX-SE domain had difficulty initiating and/or organizing for much of the early to late afternoon during IOP3, even with support of a surface convergent boundary that exhibited dryline characteristics. However, near sunset, as the dryline moved through the complex terrain of northeastern Alabama, convective coverage and intensity increased significantly. A possible tornado occurred in far northwestern Georgia as the convection exited the VORTEX-SE domain. Preliminary observations indicate terrain modification of the flow may have locally enhanced low-level convergence along the dryline, potentially explaining the convective invigoration. As part of the VORTEX-SE field campaign, multiple mobile rawinsonde teams, five mobile Doppler radars, five mobile atmospheric profiling systems, and other in-situ (disdrometers and sticknets) teams were deployed within the complex terrain of northeastern Alabama. In addition to the VORTEX-SE supported instruments, the fixed-site WSR-88D S-band polarimetric Doppler radar in Hytop, AL (KHTX) and the Advanced Radar for Meteorological and Operational Research (ARMOR) in Huntsville, AL were operating. In this presentation, an examination of the environment during IOP3 is given using a multi-sensor approach. Special focus is given to the Doppler radar and profiling observations within the terrain during the time of dryline propagation and increase in convective coverage/intensity.