Evaluation of High‐Resolution Numerical Simulations of Storm Initiation and Intensification of a Multi‐Cell Thunderstorm in Shanghai

Abstract

Abstract

Abstract This study explores the potential of operating numerical weather prediction (NWP) models at hectometer‐scale resolution to forecast a locally triggered and rapidly evolving thunderstorm over Shanghai on 8 August 2024. Two simulations are conducted using the Weather Research and Forecasting (WRF) model at convection‐permitting resolution (1 km) and large‐eddy‐resolving resolution (200 m), supplemented by a sensitivity experiment designed to clarify the lifting mechanisms responsible for convection initiation (CI). Results show that both simulations capture the basic storm evolution and overall morphology. Increasing horizontal resolution substantially alters the representation of pre‐convective boundary‐layer dynamics. The hectometer‐scale simulation explicitly resolves stronger and finer‐scale buoyant thermals, leading to earlier and more widespread CI compared to the kilometer‐scale simulation. Differences in storm evolution across resolutions are primarily caused by resolution‐dependent dynamical forcing and the resulting microphysical feedback. Stronger resolved updrafts at hectometer scale enhance ice‐phase hydrometeor production and cold pool strength, resulting in more intense simulated precipitation, surface winds, and hail relative to the kilometer‐scale simulation. However, refining grid spacing alone does not guarantee improved storm intensity or organization if the large‐scale environment is not well represented. These findings provide insight into both the benefits and the remaining challenges of applying hectometer‐scale numerical modeling to operational convective storm prediction.