Based on meteorological observation data, Doppler weather radar observation data and ERA5 hourly reanalysis data, the heavy hail weathers in Tongwei County of Gansu Province on May 30 and 31, 2020 were analyzed. The results are as follows: (1) The hail process on May 30 was a dry hail process, while the process on May 31 was a mixed strong convection with wet hail process. (2) Both two processes occurred during developing and moving eastward of the same low-trough, and the difference of influence system at 700 hPa led to difference of water vapor and energy conditions in middle and low levels, which was the main reason for occurrence of dry and wet hail. (3) The diagnostic analysis of physical quantities showed that the energy on May 31 was higher, the water vapor condition was better, and the static instability and convective instability were stronger than those on May 30, so the hail diameter was larger and precipitation intensity was stronger. (4) On the radar PPI image of reflectivity，the meso-scale characteristics of the two processes were obviously different, which was very helpful for classification and identification of severe convective nearly warning.

Based on daily observation data and disaster data from automatic weather stations in Hedong region of Gansu Province from 2008 to 2017, the 75 hail cases were selected with some standards and divided into three types according to main weather influencing system of hail and mesoscale diagnostic method, including the northwestern airstream, the low trough and the low vortex types. Then statistical characteristics of radar products and radar echo feature under the three weather types of hail were compared, and the typical hail cases were chosen to verify the results. The results show that the maximum reflectivity (Z_max) and the height of maximum reflectivity ( H_{Z_{\mathrm{m}\mathrm{a}\mathrm{x}}}) had relatively little differences under the three weather types of hail, Z_max was above 50 dBZ and H_{Z_{\mathrm{m}\mathrm{a}\mathrm{x}}} was above 2.0 km. There were significant differences in echo top height (ET), core area thickness (H), center height of echo reflectivity above 45 dBZ (H_{45 dBZ}), the maximum height of storm body echo reflectivity equal to or more than 30 dBZ (TOP), vertically integrated liquid water content (VIL), and the density of vertically integrated liquid water content (VILD). The H, H_{45 dBZ}, TOP and VIL of the northwestern airstream type were significantly higher than those of other types, and ET of the low trough type and VILD of the low vortex type were lower. The frequencies of overhang echo for the three types of hail weather were all higher than 61.0%. The frequencies of three body scattering and side-lobe echo for the the low trough type were 35.5% and 48.4%, respectively, and the probability of bounded weak echo was 12.9%. The frequencies of bounded weak echo area for both of the northwestern airstream type and the low vortex type were higher than 38.5%. The indicators of three body scattering and side-lobe echo could predict the hail weather 18 to 30 minutes in advance, which had some significance in hail weather forecast.

Based on the methods of value similarity and shape similarity, the consistency characteristics of the echo parameters of two strong convective cell pairs during a strong convective weather process caused by multiple convective monomers in Dalou Mountains in Guizhou Province on April 30, 2015 were analyzed and the time shift (phase shift) technology and mathematical statistical methods were used to analyze the similarity of the convective characteristic parameters of strong convective cell pairs. The results are as follows: (1) The value similarity of the maximum echo intensity Z_max, 0 dBZ height H₀, and 45 dBZ height H₄₅ of the cell pairs were relatively higher, but for the vertical cumulative liquid water content (VIL) it was relatively poor. (2) After processing by using the time shift technique, the change trends of the characteristic parameters of the two cell pairs were more consistent and the degree of similarity was higher. (3) The fluctuation periods of Z_max and VIL of both two cell pairs had good consistency, and fluctuation periods of H₀ and H₄₅ of C and D cell pair had better consistency. (4) The main reason for the poor value similarity of VIL of the cell pairs was the difference in the value of the radar reflectivity factor Z of each scan layer and the vertical height of Z.

Based on the hourly precipitation data from April to September during 1960-2019 at 9 national meteorological stations and 400 regional meteorological stations built year by year in Longnan of Gansu Province from 2008 to 2019, NCEP FNL 1°×1° reanalysis data and MICAPS data, the spatial-temporal distribution and mesoscale characteristics of short-time heavy precipitation in Longnan of Gansu Province were analyzed. The results are as follows: (1) The occurrence frequency of short-time heavy precipitation in Longnan became more from the northwest to the southeast, with two relatively concentrated areas. The short-time heavy precipitation with rainfall intensity greater than 50 mm·h^-1 occurred in Cheng county, Hui county and Kang county in the east of Longnan. The occurrence frequencies of short-time heavy precipitation and rainstorm were more in the southeast of Longnan, and for short-time heavy precipitation it was also relatively high in the mountainous areas in the northwest. (2) Since 1960, the stations occurring short-time heavy precipitation in Longnan increased slowly.The monthly variation showed a single-peak type, with the maximum in August and accounting for 37.5% of the total stations occurring short-time heavy precipitation. The ten-day variation presented a double-peak type, with two peaks in early July and early August, respectively. The stations occurring short-time heavy precipitation was the most from late July to mid-August, accounting for 47.2% of the total stations. Diurnal variation showed that there was more short-time heavy precipitation at night than in the day, there were multiple peaks. The stations occurring short-time heavy precipitation increased significantly since 15:00 BST. The diurnal peaks of short-time heavy precipitation occurred at 23:00 BST, accounting for 9.4% of the total stations. (3) The short-time heavy precipitation in Longnan was closely linked to rainstorms. The mesoscale concept modes of short-time heavy precipitation in Longnan mainly showed three types, including low vortex shear, northwest air flow following the trough moving eastward and the southwest air flow beside the sub-tropical high.

Based on the monitoring data of VLF/LF three-dimensional lightning positioning system, MICAPS routine observation data and ground hail observation data, the lightning activity characteristics of a large-scale disaster-causing hail weather process in the slope transition zone of the Yunnan-Guizhou Plateau were analyzed, and the relation between lightning activity and hail falling was discussed. The results are as follows: (1) The stable southern trough in upper level cooperated with the lower level shear line, lower level jet and surface convergence line, which triggered the large-scale hail weather process. (2) The negative ground lightning dominated during the hail weather process, followed by cloud lightning and positive ground lightning. The frequency of total lightning appeared ‘jump increase’ and ‘sharp drop’ phenomena before and after the hail falling in hail area, respectively, and the jump characteristic of lightning frequency change rate more than two standard deviations (2σDFRDT) was obvious before the hail falling, the 2σDFRDT jump signal and peak of total lightning frequency were 20 minutes and 13 minutes ahead of the hail falling, respectively, so two signals had warning indicative significance for hail falling, while the former was better than the later. (3) The spatial distribution of lightning was basically consistent with the moving path of hail cloud, which was an indicator to the development and movement of hail cloud, and the hail areas were mainly located in the right side of lightning position.

Based on the data of aerological and surface meteorological observation for many years，the trend of water vapor content and its transport over Lanzhou city were analyzed deeply. Results are as follows：（1）The water vapor content and its transport are relatively more in summer than that in winter，and the water vapor content increases from Feb to Jul，decreases from Sep to Jan，and keeps invariable in Jul and Aug；nearly 97% water vapor content concentrates below the height of 400 hPa；（2）The trend of water vapor content distinctly corresponds to the change of precipitation，rainy days and temperature，but also there are some differences；（ 3 ）Over Lanzhou city，the large center of water vapor transport is near the height of 500 hPa，the maximum diurnal variation of water vapor is at the layer of 700 ～ 600 hPa in winter，and these are obviously different from those over the east of China.

Abstract:Using the data of Dopplor radar and reanalysis data of NECP/NCAR, the rainstorm process which occurred on August 27,
28 in 2003 in Gansu province was analyzed in this paper. The results show that the reason of veer degree of zero speed line differing
from one side to the other side of the station was the big scale confluence adding on the warm advection, the structure offered advan-
tageous vertical vapor transportation and confluence rising for producing and maintaining strong precipitation; upwind section and
middle-small scale confluence ( divergence) were in close connection with strong precipitation and that is an important index on pre-
cipitation prediction; the region and amount of precipitation have connection with the amount of vapor flux transportation and the de-
gree of vapor confluence.