Rare winter‐thunderstorms with hail overnight 12/13 December 2019 over Delhi and its vicinity: an observational study

Abstract

A rare overnight thunderstorm with hail on 12/13 December 2019 over Delhi was driven by a Westerly Disturbance (WD) and analysed with the aid of multi‐platform observations. The Doppler weather radar (DWR) detected high reflectivity values (>50dBZ), indicating hail within towering convective clouds. In‐situ measurements showed intense rainfall (totalling ~134mm), accompanied by strong wind gusts and a rapid pressure drop. Satellite data revealed widespread cold cloud tops (<−50°C) associated with the deep convection, while radiosonde profiles indicated atmospheric instability and veering winds during its passage. Lightning observations confirmed energetic convective updrafts. The event highlights the impact of WDs in triggering severe and rare winter convective storms over northern India.