Abstract: Currently, downburst identification and warning algorithms based on weather radar in China cannot effectively estimate the intensity and wind speed of downbursts. The Wuhan Institute of Heavy Rain, China Meteorological Administration, has newly developed a method for estimating the extreme wind speed of thunderstorm gales based on dual-polarization weather radar hydrometeor classification products (Extreme wind speed Estimation method based on Hydrometeor Classification products from dual-polarization weather radar, EESonHC). Focusing on the downburst event that occurred in Guizhou on May 4, 2025 (hereinafter referred to as the "5.04" downburst event), this study utilized sounding meteorological data, ground automatic weather station observations, and Guiyang dual-polarization weather radar products to analyze the application effectiveness and influencing factors of the EESonHC method in supercell storms over the southwestern Guizhou mountainous areas. The results are as follows. the EESonHC method accurately captured the temporal evolution characteristics of surface winds generated by the supercell storm near Guiyang, estimating extreme wind speeds slightly higher than surface observations with a 10-minute lead time; it effectively distinguished which of the two storm cells during the Guizhou "5.04" event produced downburst wind speeds exceeding 25 m·s⁻¹; due to severe terrain blockage affecting the 0.5° elevation radar data in Guizhou's mountainous areas, extreme wind speeds estimated using 1.5° elevation radar data were more accurate; the vertical acceleration threshold within the storm cell region in the EESonHC method is related to raindrop size distribution characteristics; however, thresholds established based on case studies from North China and the Jianghuai regions remain applicable to Guizhou. This demonstrates that the EESonHC method is not only suitable for plain regions such as North China and the Jianghuai regions, but also for mountainous regions of Southwest China; it is applicable not only to multicell storms but also to supercell storms.