Structural Characteristics and Developmental Analysis of the Rare Hail Supercell in the Northeast Yunnan-Guizhou Plateau

Using conventional high-altitude detection， automatic weather station observations， radar detection and ERA-Interim Reanalysis， and the numerical simulation model on May 4， 2020， in the northeast of Yunnan-Guizhou plateau rare large hailstones （70 mm diameter， the breakthrough at present since the record of Guizhou can query the hail history） process is analyzed and simulated.The analysis shows that this rare hail weather occurred in the background of favorable environmental conditions， such as high CAPE and appropriate wet-bulb temperature 0 ℃ layer height， the warm zone before an upper trough.The synoptic system is a meso-γ isolated convective system called supercell storm.The storm is a classic supercell storm on the Doppler weather radar， and the vertical accumulated liquid water content （VIL） up to 105 kg·m-2 is an important reason for the formation of this rare large hail.The convergence line excitation and the development of small vortices are the trigger causes of supercell storm formation.The near surface cold pool is the main factor to promote the development and enhancement of supercell.The results of numerical simulation show that the supercell quickly strengthen when it reach Yangqiao， vertical rising movement of more than 15 m·s-1.Deep vorticity pairs appear in the cloud， and the positive vorticity band corresponds to the rising movement.The hailstone growth layer has a large content， which plays a key role in the development of supercell storms and the growth of hail.