December 3, 2021 - 3:00 pm
December 3, 2021 - 4:00 pm
CategoriesConvective Meteorology (Mesoscale Dynamics)
Convective Meteorology (Mesoscale Dynamics)
Radar and Thermodynamic Analysis of the Low-Level Structure of the 6 April 2018 Monroe, LA Tornadic Supercell
Friday, December 3
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During the Verification of the Origins of Rotation in Tornadoes Experiment Southeast (VORTEX-SE), a tornadic supercell near Monroe, LA was well sampled by up to five Doppler radars on 6 April 2018. This wealth of close-proximity radar data facilitates a rare high-resolution analysis of a southeast US supercell. Two mobile research radars (SR2 and SR3), the WSR-88D equivalent KULM, and two airborne radars aboard the NOAA P-3 aircraft (TAFT and TFORE) sampled the storm at close proximity for ~70 minutes through its mature phase, dissipation, and subsequent ingestion into a developing MCS segment. The 4-D wind field and reflectivity from up to five-Doppler analyses every 5 minutes are combined with 4-D Diabatic Lagrangian Analysis (DLA, Ziegler 2013a,b) retrievals, enabling analysis of the evolving low-level mesocyclone and storm-scale kinematic and thermodynamic boundaries leading up to, during, and after the dissipation of the 10-minute long EF-0 tornado. The role of these internal storm boundaries in baroclinically generating streamwise vorticity and tilting horizontal vorticity into the vertical as parcels enter the low-level main updraft is investigated. Preliminary results reveal an enhanced region of near-surface horizontal streamwise vorticity and vertical vorticity along the forward-flank convergence boundary leading up to tornadogenesis, appearing similar to a Streamwise Vorticity Current (SVC) that has been identified in simulated supercells. However, a separate local streamwise vorticity maximum in the inflow near the pendant tornado-cyclonic vortex is ingested by the backing northerly flow of the developing RFD outflow into the helical tornado-cyclonic updraft, implying a local barotropic contribution to the origin of low-level tornado-cyclonic rotation. Due to the highly-tilted tornado-cyclonic vortex in strong vertical wind shear and only moderate Convective Available Potential Energy (CAPE), along with anvil precipitation which overhangs a significant portion of the southerly inflow region, the observed structure of this storm differs from other supercells in idealized simulations of the SVC. The Compact Raman Lidar (CRL), a P-3 aircraft-mounted downward-pointing lidar that profiles boundary layer water vapor mixing ratio and temperature at high resolution, is compared to the far-field proximity sounding which was used to initialize the environment for the DLA to explore the potential impact of small-scale thermodynamic heterogeneities across the inflow warm sector on storm intensity and the development of low-level rotation.