Abstract: Based on the observation data of Huangshan area and EC reanalysis data from 1981 to 2017,and using mathematical-statistical methods,the characteristics of the summer high temperature (SHT) in Huangshan area were analyzed and the reason of a high-temperature weather process with the extreme high temperature,long duration,large intensity and wide range in July 2017 was diagnosed.The results show that the subtropical high is the main influence system of SHT.The SHT has clear spatio-temporal distribution characteristics.More specifically,the most and the second most high-temperature days are in July and August,accounting for 48% and 37%,respectively.The high temperature mainly occurs in the period from mid-July to early August.The spatial distribution of the SHT features more occurrence in basins and hilly areas and less in high-altitude mountainous areas. Meanwhile,strong subtropical high,the ridgeline stabilizing in Huangshan area,the coordination of the warming sinking air near the sub-high ridge line and low-level warm center are the main causes of the continuous high temperature in Huangshan area during July 12-29 in 2017.In addition,the inactive tropical low-value system during midsummer and few landing typhoons during high temperatures provide favorable conditions for the occurrence of persistent high temperatures.Topography,such as altitude,leads to the uneven distribution of high temperature.Besides,the position of sub-high ridgeline,subtropical high intensity,relative humidity profile,rainfall,typhoons,topography,and other factors are of great indicative significance for the forecast and early warning of high temperature.

Key words: High-temperature, Subtropical high, Mountainous area