Based on hourly precipitation data from 109 meteorological stations in Sichuan basin and 3-hourly forecast data with 0.1°×0.1° spatial resolution from GRAPESMESO model from May to September during 2017-2018, this study investigated the characteristic of key physical parameters of the occurrence and development of extreme shorttime heavy precipitation (hourly precipitation amount ≥50 mm), such as thermal instability, water vapor and dynamic conditions. A prediction model was established using random probability thought and principal component analysis method to develop the extreme shorttime heavy precipitation probability forecast product. The forecast effect evaluation showed that the TS was 24.0% when the probability was greater than or equal to 0.7. The value could be used as the reference threshold for the extreme shorttime heavy precipitation forecast. During the rainstorm process in Sichuan basin on 22 July 2019, the practical application indicated that the product had good reference meaning for the forecast of extreme shorttime heavy precipitation location.

The vertical temperature profile data of a lightning hail cloud moving from northwest to southeast over Beijing on September
14，2008 remote sensed by TP/WVP－3000 microwave radiometer are analyzed here．Referring to radar echoes and automatic weather
system precipitation data，we use the temperature data of Guanxiangtai station as the environment temperature profile when it does not
rain there，and use the temperature data of Chedaogou station as the hail cloud temperature profile when it rains there only．The evolu-
tion of temperature profile over Chedaogou station，the mean systematic errors and the temperature deference at 2，4，6 km height be-
tween two stations are studied．Results show that during the rianfall period(from 21:00 to 21:15)the temperature at the bottom of
the hail cloud is much more lower than that outside the hail cloud where it does not rain，but from the lower level to the higher level in
front of hail cloud，the temperature is much more higher than that outside the hial cloud，the difference is 4．2℃at 2 km，10．1℃at
4 km and 8．8℃at 6 km．