The Utilization of Ground-Based and Mobile Instrumentation Platforms to Dissect Lower Tropospheric Flow around the 01 April 2023 Northern Alabama Tornado during the PERiLS Field Campaign

During the early morning hours of 01 April 2023, a resurging Quasi-Linear Convective System (QLCS) produced a violent tornado in portions of North Alabama and Southern Tennessee. This tornado would prove to be amongst the strongest of tornadoes produced from this system, with maximum estimated winds of 160 miles per hour (71.5 m/s). Further, this tornado formed within a region of deep convection with reflectivity values exceeding 50 to 55 dBZ as seen from the National Weather Service Weather Surveillance Radar - 1988 Doppler (WSR-88D) located in Hytop, Alabama (KHTX). The 31 March - 01 April severe weather outbreak across North Alabama was the focus region for the fourth intensive observation period (IOP) for the 2023 portion of the Propagation, Evolution, and Rotation in Linear Storms (PERiLS) field campaign. Numerous mobile radars, wind profilers, lidars, sticknet stations, and more provided by a number of universities and government agencies were configured across this region to gather information on the ever-changing environment ahead of a tornadic QLCS. The PERiLS platform data will provide key details to the evolving low-level environment in the time leading up to tornadogenesis with a focus on the dynamic and kinematic variability in the lower atmosphere. A balloon sounding was launched from the Severe Weather Institute - Radar and Lightning Laboratory (SWIRLL) located on the campus of The University of Alabama in Huntsville (UAH) at 08Z, approximately 28 km to the southwest and less than 10 minutes prior to tornadogenesis. This sounding closely followed the QLCS and was within 18 km of the mesovortex as the tornado formed. As is typical during the late cool season in the Southeast, the pre-storm environment was indicative of a high-shear, low-CAPE (HSLC) set-up with CAPE values near 600 J/kg and 0-6 km shear values approaching 70 knots. In the hours leading to tornadogenesis, a steady increase in Storm-Relative Helicity (SRH) was noted across all PERiLS locations, with values increasing to near 600 to 800 m2/s2 by 08Z. Dual-Doppler Analyses (DDAs) between the KHTX S-band radar and the Advanced Radar for Meteorological and Operational Research (ARMOR) C-band radar at Huntsville International Airport will be performed to identify the orientation of the wind-field near the time of tornadogenesis and the rapid intensification of the tornado during its early life cycle. By utilizing the PERiLS platform data, observations from SWIRLL, and the two radars for DDAs, the QLCS will be analyzed from the Mississippi/Alabama state line through tornado dissipation. The use of this data will document the destabilization of the Nocturnal Boundary Layer (NBL) and reveal how kinematic and dynamic variations influenced the low-level flow over the PERiLS domain.