DSD Characteristics and Evolution of the Leading Stratiform Region of a Tornadic QLCS during PERiLS-2022 IOP#2 (30 March 2022).

This study examines the development and evolution of a tornadic quasi-linear convective system (QLCS) during Intensive Observation Period 2 (IOP2) of the 2022 Propagation, Evolution, and Rotation in Linear Storms (PERiLS) field program, with specific emphasis on the development and evolution of the leading stratiform (LS) precipitation shield. Four Portable In Situ Precipitation Systems (PIPS) equipped with Parsivel2 disdrometers gathered DSD, kinematic, and thermodynamic observations at three different locations along the line (including in close proximity to an EF-1 tornado). Each PIPS sampled the leading stratiform, convective, and trailing stratiform regions of the QLCS as it passed over their locations.

Motivated by a need to understand the potential impacts on tornado development within the line of near-surface thermodynamic and kinematic changes in the inflow region of the QLCS associated with LS precipitation, we employ a simple raindrop trajectory model to investigate the influence of size sorting from the storm-relative winds on DSD evolution between the radar level and the surface. The model uses the method of moments and a constrained-gamma DSD model to initialize DSDs from gridded NEXRAD radar observations of reflectivity (Z) and differential reflectivity (ZDR). It then incorporates low-level wind profiles from nearby special PERiLS proximity soundings and initializes multiple trajectories for several discrete drop-size bins for the retrieved DSDs at each radar grid point. We analytically solve the surface endpoints of the trajectories allowing us to compare the resulting model DSDs with those observed by the PIPS and to quantify the effect of size sorting in that layer. We will also attempt to quantify the impact of evaporative cooling on the near-surface thermodynamic profile in the inflow/LS precipitation region using a combination of direct observations from the PIPS, proximity soundings, and the trajectory model.