A Preliminary Study on the Nocturnal Evolution of PERILS 2023 IOP3's Supercell to QLCS Development

The Propagation Evolution and Rotation of Linear Storms (PERiLS) field campaign deployed mobile facilities on 24 March 2023 to the Mississippi Delta region. During the intensive operational period, a storm system passed over the instrumentation network that later produced multiple tornadoes in Mississippi and North Alabama. An EF4 tornado produced from this system went on to devastate the communities of Rolling Fork and Silver City. This mesoscale convective system displayed fascinating evolution beginning from supercells which later merged into a Quasi-Linear Convective System. This preliminary study aimed to document and understand the changes in environmental parameters and associated convective-scale structures as the system moved from initiation over the PERiLS network to North Alabama. The analysis methodology utilizes ground based PERiLS assets such as Lidars, Profilers, and balloon and HRRR model Soundings covering the storm evolution between the inception over the PERiLS domain and North Alabama using available ground based instrumentation. Other fixed-base sites being utilized are the Greenwood, Mississippi and Starkville, Mississippi NOAA 915 MHz radar wind profilers and a 449 MHz radar wind profiler at Courtland, Alabama. The ARMOR radar at the Huntsville Airport will support single Doppler analysis of QLCS structure along with wind profiles from VAD analyses. The HRRR model soundings are compared with the soundings launched in the PERiLS network and provide context for the ground based instrumentation. More ground based sites such as ASOS and Mesowest (also Weather Underground) stations and additional instrumentation such as nearby radars will be added as needed to supplement HRRR data and document the cold pool characteristics of the QLCS. Additionally, Lightning density plots from NALMA and the NSSL LMA network will be added for more context. Sounding data from the PERiLS network primarily focused on CAPE, SRH, and Shear parameters. Preliminary results from the PERiLS soundings indicated that two environments were present in the storm system initiation zone. These environments were characterized by High Shear High Cape and High Shear Low Cape. The High Shear High Cape environment appeared to persist for the EF4 tornadic cell deep into Mississippi. Overall there was high surface variability throughout the storm system at the initiation site with the boundary layer at its lowest around the Rolling Fork tornadic cell. These storms may have maintained different environments despite being linked shortly before becoming a QLCS in North Alabama. It should be noted that the Storm Prediction Center records 35 tornado reports from initialization to North Alabama with 21 tornado reports in Mississippi and 14 in North Alabama. This storm system was tornadic from 0057 UTC to 0628 UTC, exceeding five hours of tornadic activity.