Radar Signatures and Near Storm Environmental Parameters of Severe Thunderstorms across Northern New York and Vermont

The motivation of this project was to investigate WSR-88D Doppler radar data and nearstorm environments to improve severe thunderstorm detection and verification across northern New York and Vermont. This research focused on assessing instability and shear parameters to identify near-storm environments conducive for severe thunderstorm development, along with establishing severe thunderstorm warning thresholds based on reflectivity (Z) and differential reflectivity (Zdr) values and heights. All severe thunderstorm warnings and severe weather reports from the National Weather Service (NWS) Burlington, VT, (BTV) County Warning Area (CWA) from 2017 through 2019 during May, June, July, and August were examined. Rapid Refresh (RAP) proximity soundings were utilized to evaluate near-storm thermodynamic and vertical shear parameters. Storms were subsequently classified based on WSR-88D radar reflectivity characteristics into four distinct types; single cell (SC), multi-cell cluster (MCC), multi-cell linear (MCL), and supercell (SP). Radar interrogation of the 50 and 60 dBZ heights were examined, including vertical cross sections of reflectivity and differential reflectivity. An evaluation of traditional height-based reflectivity thresholds at 0°C, -10°C, and -20°C isotherm levels were investigated to identify critical warning thresholds. The four distinct convective modes demonstrated a large range of environmental parameters conducive for producing severe weather across the BTV CWA. MCL events had the highest shear and lowest instability parameters, while displaying the lowest (Z) and (Zdr) columns. Additionally, if a Zdr column of 3 dB or greater was present above the -10°C isotherm, severe weather was observed 89% of the time and 63% of the time if above the 0°C isotherm.