Forecast Error and Predictability for the Warm-sector and the Frontal Rainstorm in South China

In south China, warm-sector rainstorms are significantly different from the traditional frontal rainstorms due to complex mechanism, which brings great challenges to their forecast. In this study, based on ensemble forecasting, the high-resolution mesoscale numerical forecast model WRF was used to investigate the effect of initial errors on a warmsector rainstorm and a frontal rainstorm under the same circulation in south China, respectively. We analyzed the sensitivity of forecast errors to the initial errors and their evolution characteristics for the warm-sector and the frontal rainstorm. Additionally, the difference of the predictability was compared via adjusting the initial values of the GOOD member and the BAD member. Compared with the frontal rainstorm, the warm-sector rainstorm was more sensitive to initial error, which increased faster in the warm-sector. Furthermore, the magnitude of error in the warm-sector rainstorm was obviously larger than that of the frontal rainstorm, while the spatial scale of the error was smaller. Similarly, both types of the rainstorm were limited by practical predictability and inherent predictability, while the nonlinear increase characteristics occurred to be more distinct in the warm-sector rainstorm, resulting in the lower inherent predictability.The comparison between the warm-sector rainstorm and the frontal rainstorm revealed that the forecast field was closer to the real situation derived from more accurate initial errors, but only the increase rate in the frontal rainstorm was restrained evidently.

Synergistic Effect of the Planetary-scale Disturbance, Typhoon and Meso-β-scale Convective Vortex on the Extremely Intense Rainstorm on 20 July 2021 in Zhengzhou

On 20 July 2021,northern Henan Province in China experienced catastrophic flooding as a result of an extremely intense rainstorm,with a record-breaking hourly rainfall of 201.9 mm during 0800–0900 UTC and daily accumulated rainfall in Zhengzhou City exceeding 600 mm(“Zhengzhou 7.20 rainstorm”for short).The multi-scale dynamical and thermodynamical mechanisms for this rainstorm are investigated based on station-observed and ERA-5 reanalysis datasets.The backward trajectory tracking shows that the warm,moist air from the northwestern Pacific was mainly transported toward Henan Province by confluent southeasterlies on the northern side of a strong typhoon In-Fa(2021),with the convergent southerlies associated with a weaker typhoon Cempaka(2021)concurrently transporting moisture northward from South China Sea,supporting the rainstorm.In the upper troposphere,two equatorward-intruding potential vorticity(PV)streamers within the planetary-scale wave train were located over northern Henan Province,forming significant divergent flow aloft to induce stronger ascending motion locally.Moreover,the converged moist air was also blocked by the mountains in western Henan Province and forced to rise so that a deep meso-β-scale convective vortex(MβCV)was induced over the west of Zhengzhou City.The PV budget analyses demonstrate that the MβCV development was attributed to the positive feedback between the rainfall-related diabatic heating and high-PV under the strong upward PV advection during the Zhengzhou 7.20 rainstorm.Importantly,the MβCV was forced by upper-level larger-scale westerlies becoming eastward-sloping,which allowed the mixtures of abundant raindrops and hydrometeors to ascend slantwise and accumulate just over Zhengzhou City,resulting in the record-breaking hourly rainfall locally.

Pore Characteristic Design Method of High-strength Pervious Concrete Based on the Mechanical Properties and Rainstorm Waterlogging Resistance

High-strength pervious concrete(HSPC) with porosity ranging from 0.08% to 2.011% was prepared. The mechanical properties and rainstorm waterlogging resistance of HSPC were evaluated,and a design method of HSPC pore characteristics(porosity and pore diameter) based on the mechanical properties and rainstorm waterlogging resistance was proposed. The results showed that the reduction of effective cross-sectional area caused by artificial channels was the main factor affecting flexural strength but had limited influence on compressive strength. Compared with the concrete matrix without artificial channels,the compressive strength of HSPC with porosity of 2.011% decreased by 7.4%, while the flexural strength decreased by 48.3%. The permeability coefficient of HSPC can reach 16.35 mm/s even at low porosity(2.011%).HSPC can meet the requirements of no rainstorm waterlogging, even if exposed to 100-year rainstorms. When the mechanical properties and rainstorm waterlogging resistance are compromised, the recommended porosity ranges from 1.1% to 3.5%, and the recommended pore diameter ranges from 0.8 to 2.7 mm.

Effect of Fatigue Loading on the Mechanical Properties and Resistance of High-strength Straight-hole Recycled Pervious Concrete to Rainstorm-based Waterlogging

A novel high-strength straight-hole recycled pervious concrete(HSRPC)for the secondary highway pavement was prepared in this paper.This study aimed to investigate the effect of porosity(0.126%,0.502%,and 1.13%),vehicle loading stress level(0.5 and 0.8)and service life on the resistance to rainstormbased waterlogging of HSRPC under fatigue loading.The mechanical properties of HSRPC in terms of flexural strength and dynamic elastic modulus were studied.The waterlogging resistance of HSRPC was described by surface water depth and drainage time.The microstructure of HSRPC were observed with scanning electron microscopy(SEM).Results showed that although the dynamic elastic modulus and flexural strength of HSRPC decreased with the increasing number of fatigue loading,the flexural strength of HSRPC was still greater than5 MPa after design service life of 20 years.After 2.5×10^(5)times of fatigue loading,the permeability coefficient of HSRPC with a porosity of 0.502%and 1.13%increased by 18.4%and 22.9%,respectively;while the permeability coefficient of HSRPC with 0.126%porosity dropped to 0.35 mm/s.The maximum surface water depth of HSRPC with a porosity of 0.126%,0.502%,and 1.13%were 8,5 and 4 mm,respectively.SEM results showed that fatigue loading expanded the number and width of cracks around the tiny pores in HSRPC.

Reflection on China's Disaster Prevention and Mitigation Construction after Rainstorm and Snowstorm

On July 10,2004,Beijing was hit by the rainstorm that has not been seen for many years,which caused water accumulation in many places of the urban area,power supply interruption in many places,and traffic paralysis for nearly 5 h. On July 12,2004,the rainstorm in Shanghai lasted less than 1 h,but it caused 7 deaths,more than 20 injuries,extensive power outages and traffic paralysis. At the end of 2005,the continuous snowfall in Weihai City of Shandong Province for half a month caused direct economic losses of over 200 million yuan,and the continuous heavy snowfall had a serious impact on people’s lives. From July 17 to 23,2021,Henan Province suffered a rare extremely heavy rainstorm in history,with a direct economic loss of 120.6 billion yuan. Faced with such urban meteorological disasters and other types of urban disasters,combined with the current situation of disaster prevention and reduction in China,what will managers,decision-makers,and experts and scholars think about from them.

Analysis of a Local Rainstorm in Central Inner Mongolia

Based on conventional observation data,satellite cloud image data and new generation Doppler radar data,the local rainstorm weather situation and physical quantities in Ulanqab City from 08:00 to 20:00 on June 24,2019 were analyzed by means of synoptic methods.The results show that the local rainstorm was caused by the forward trough system and the convergence of warm and cold air,and triggered by the low-level jet and the surface convergence line.The splitting and merging of cloud clusters in satellite cloud images and strong radar echoes had a good guiding effect on short-term heavy precipitation.

Analysis on the Cause and Forecast Deviation of an Extreme Rainstorm in Changsha Urban Area

Using NCEP reanalysis data,high-altitude and ground observation data,numerical model data,satellite and radar data,formation cause and forecast deviation of an extreme rainstorm process in Changsha urban area at night on June 9,2020 were analyzed.The results showed that(1)the extreme rainstorm process developed near the surface convergence line,with strong localization,short duration and large hourly rainfall intensity.(2)Under the high temperature and high humidity environment,the low-level cold advection and the hot low-pressure system interacted,and the potential con-vective unstable energy was released,and a strong convective weather was formed.(3)The convergence of water vapor in the lower layer and the strong upward movement provided sufficient water vapor for the rainstorm.The low-centroid thunderstorm was the main reason for the extreme rainstorm.(4)The forecast deviation of the numerical model to the low-level shear line and the mesoscale convergence line was an important reason for the forecast deviation of the heavy rainfall area.

Analysis of Rainstorm Process over Henan Province of China in July 2021

Based on the data from the China National Meteorological Station and the fifth-generation reanalysis data of the European Center for Medium-Range Weather Forecasts, we investigated and examined the precipitation, circulation, and dynamic conditions of the rainstorm in Henan in July 2021. The results show that: 1) This precipitation is of very heavy rainfall level, beginning on the 19th and lasting until the 21st, with a 3-hour cumulative precipitation of more than 200 mm at Zhengzhou station at 19:00 on the 20th. The major focus of this precipitation is in Zhengzhou, Henan Province, and it also radiates to Jiaozuo, Xinxiang, Kaifeng, Xuchang, Pingdingshan, Luoyang, Luohe, and other places. 2) The Western Pacific Subtropical High (WPSH), typhoons “In-Fa” and “Cempaka”, as well as the less dynamic strengthening of the Eurasian trough ridge structure, all contributed to the short-term maintenance of the favorable large-scale circulation background and water vapor conditions for this rainstorm in Henan. 3) The vertical structure of low-level convergence and high-level dispersion near Zhengzhou, together with the topographic blocking and lifting impact, produced favorable dynamic lifting conditions for this rainstorm.

Climatology of Shear Line and Related Rainstorm over the Southern Yangtze River Valley Based on an Improved Intelligent Identification Method

Based on four reanalysis datasets including CMA-RA,ERA5,ERA-Interim,and FNL,this paper proposes an improved intelligent method for shear line identification by introducing a second-order zonal-wind shear.Climatic characteristics of shear lines and related rainstorms over the Southern Yangtze River Valley(SYRV)during the summers(June-August)from 2008 to 2018 are then analyzed by using two types of unsupervised machine learning algorithm,namely the t-distributed stochastic neighbor embedding method(t-SNE)and the k-means clustering method.The results are as follows:(1)The reproducibility of the 850 hPa wind fields over the SYRV using China’s reanalysis product CMARA is superior to that of European and American products including ERA5,ERA-Interim,and FNL.(2)Theory and observations indicate that the introduction of a second-order zonal-wind shear criterion can effectively eliminate the continuous cyclonic curvature of the wind field and identify shear lines with significant discontinuities.(3)The occurrence frequency of shear lines appearing in the daytime and nighttime is almost equal,but the intensity and the accompanying rainstorm have a clear diurnal variation:they are significantly stronger during daytime than those at nighttime.(4)Half(47%)of the shear lines can cause short-duration rainstorms(≥20 mm(3h)^(-1)),and shear line rainstorms account for one-sixth(16%)of the total summer short-duration rainstorms.Rainstorms caused by shear lines are significantly stronger than that caused by other synoptic forcing.(5)Under the influence of stronger water vapor transport and barotropic instability,shear lines and related rainstorms in the north and middle of the SYRV are stronger than those in the south.

Mechanism Analysis of " 7·21" Extremely Heavy Rainstorm Process in 2012 in Beijing

Extremely heavy rainstorm occurred in Beijing on July 21,2012, which was the most serious since 1961. Based on analyzing the precipitation characteristics, formation mechanism of the rainstorm process was analyzed. Results showed that when the precipitation process occurred, it was stable east-high and west-low situation at 500 hPa, and there was a steady stream of water vapor transportation at middle and low layers and strong vertical ascending motion at 700 hPa. The distribution of physical quantity field （relative humidity, vorticity and divergence） showed that they were all benefited to the formation of rainstorm. Then, falling zone of rainstorm and the movement of rain belt, generation, development and weakening of precipitation were analyzed. Finally, according to circulation situation and the distribution of physical quantity at each layer, vertical distribu- tion of physical quantity and distribution of water vapor and jet stream, ＂7 · 21＂ rainstorm model was summarized.

Soil erosion of unpaved loess roads subjected to an extreme rainstorm event: a case study of the Jiuyuangou watershed on the Loess Plateau, China

Rainfall can cause serious soil loss in the Loess Plateau hilly and gully region, but little focus has been placed on the extreme rainstorm effects on unpaved loess road soil erosion. A field survey method was used to investigate the erosional effects of the '7·26' heavy rainfall event on unpaved loess roads in the Jiuyuangou watershed of the Loess Plateau, China. The results showed that the average and maximum widths of the eroded gullies that formed on the unpaved roads were 0.65-1.48 m and 1.00-3.60 m, respectively. The average and maximum depths of theeroded gullies were 0.42-1.13 m and 0.75-4.30 m, respectively. The average width-to-depth ratio was 1.31, indicating that the widening effect was greater than the downcutting effect in the eroded gullies. In addition, the gully density ranged from 0.07 to 0.29 m m-2, and the road surface dissection degree ranged from 0.03 to 0.41 km2 km-2. Eroded gullies generally developed at the slope toe of the cut bank side. The average eroded gully width and depth at turns in the road were 1.47-2.64 times and 1.30-3.47 times greater, respectively, than those in other road sections. The road erosion modulus increased from the upper section to the lower section of the roads. The average road erosion modulus of the study catchment was 235,000 t km-2. Turns in the road were associated with collapses, sinkholes and other gravitational erosion phenomena. The amount of road erosion under extreme rainfall conditions is mainly related to the interactions among road length, width, slope and soil bulk density. Our results provide a useful reference for developing further measures for preventing road erosion on the Loess Plateau.

CHARACTERISTICS OF THE MERIDIONALLY ORIENTED SHEAR LINES OVER THE TIBETAN PLATEAU AND ITS RELATIONSHIP WITH RAINSTORMS IN THE BOREAL SUMMER HALF-YEAR

In this paper,European Center for Medium-Range Weather Forecasts(ECMWF)Reanalysis-Interim(ERAInterim)data and daily precipitation data in China from May to October during 1981-2016 are used to study the climatic characteristics of the meridionally oriented shear lines(MSLs)over the Tibetan Plateau(TP).The relationship between the MSL and rainstorms in the eastern TP and neighboring areas of the TP during the boreal summer half-year is also investigated.An objective method,which uses a combination of three parameters,i.e.the zonal shear of the meridional wind,the relative vorticity and the zero line of meridional wind,is adopted to identify the shear line.The results show that there are two high-occurrence centers of MSL.One is over the central TP(near 90°E)and the other is over the steep slope area of the eastern TP.Fewer MSLs are found along the Yarlung Zangbo River over the western TP and the southern Tibet.There are averagely 42.2 MSL days in each boreal summer half-year.The number of MSL days reaches the maximum of 62 in 2014 and the minimum of 22 in 2006.July and October witness the maximum of 10.2 MSL days/year and the minimum of 4.2 MSL days/year,respectively.The annual number of the MSL days shows periodicities of 2-4 and 4-6 years,which is quite similar to those of the MSL rainstorm days.In the neighboring areas of the TP,nearly56%of the MSLs lead to rainstorms,and nearly 40%of rainstorms are caused by the MSLs,indicating a close relationship between the MSLs and rainstorms in this region.

Simulation of a torrential rainstorm in Xinjiang and gravity wave analysis

We used a weather research and forecasting model to simulate a torrential rainstorm that occurred in Xinjiang, China during June 16–17, 2016. The model successfully simulated the rainfall area, precipitation intensity, and changes in precipitation. We identified a clear wave signal using the two-dimensional fast Fourier transform method; the waves propagated westwards, with wavelengths of 45–20 km, periods of 50–120 min, and phase velocities mainly concentrated in the-25 m/s to-10 m/s range. The results of wavelet cross-spectral analysis further confirmed that the waves were gravity waves, peaking at 11：00 UTC, June 17, 2016. The gravity wave signal was identified along 79.17–79.93°E, 81.35–81.45°E and 81.5–81.83°E. The gravity waves detected along 81.5–81.83°E corresponded well with precipitation that accumulated in 1 h, indicating that gravity waves could be considered a rainstorm precursor in future precipitation forecasts.

Study on the Influences of GWDO Parameterization Scheme and Terrain on a Rainstorm in Dabie Mountain

[Objective] The research aimed to study the influences of GWDO parameterization scheme and terrain on a rainstorm in Dabie Mountain.[Method] By using NCEP/NCAR 1°×1° analytical data,the conventional and unconventional ground observation data,WRFV3.1.1 version of non-hydrostatic balance meso-scale mode,a meso-scale shear line rainstorm process which happened in Dabie Mountain zone during 05:00-14:00 on June 21,2008 was carried out the diagnostic analysis and numerical test.In the control experiment,the gravity wave drag by orography(GWDO) parameterization scheme was added.The influences of GWDO parameterization scheme and terrain on the rainstorm process were discussed respectively by the sensitivity test.[Result] The orography dragging coefficient had the good improvement role on the rainstorm intensity or falling zone.The result had the very big difference when considering or non-considering the orography dragging coefficient.After the parameterization scheme was added,the rainstorm intensity or falling zone was better than that of non-addition.When there was no dragging coefficient,the shear line disturbance was strong,and the gravity wave activity was obvious.The precipitation was stronger in the zone where the gravity wave was obvious.The terrain in Dabie Mountain and the surrounding place also had the important effect on the shear line precipitation.When the terrain in Dabie Mountain was removed,the precipitation intensity on the shear line increased significantly,and the strengthening of rain belt in the west was the most obvious.When the terrain in the southeast of Dabie Mountain was removed,the precipitation in the east had the obvious increasing effect.The terrain wasn’t favorable for the rainstorm strengthening.The intensity variation of rain belt not only related to the terrain,but also related to the disturbance variation on the shear line.[Conclusion] The research provided the theory basis for the prediction and forecast of rainstorm.

AN OBSERVATIONAL ANALYSIS OF A TORRENTIAL RAINSTORM IN THE WARM SECTOR OF SOUTH CHINA COASTAL AREAS

On May 20 th 2007, a brief but severe downpour rainstorm occurred in the coastal areas of Maoming and Yangjiang with rainfall of 115 mm per hour. Data from NCEP/NCAR reanalysis with 1°×1° resolution, Doppler weather radar, conventional surface observations, high-altitude radiosonde and wind profiler radar were used to analyze characteristics and contributions of synoptic scale and mesoscale systems during this torrential rainstorm. The results showed that:(1) the storm was caused by a quasi-linear mesoscale convective system(MCS) and the slow-movement of this system was the primary trigger of the torrential downpour;(2) water vapor was abundant, nearly saturated and in steady state throughout the atmosphere before the storm; intrusion of the weak dry and cold air in the middle level and a striking "dry above and wet below " structure had increased the atmospheric instability;(3) low-level southwesterly airflow from a low pressure(trough) at the Beibu Gulf provided abundant water vapor at the onset of the rainstorm; a deep dry layer was formed by dry and cold air behind the high-level trough, which facilitated latent heat release;upper-level divergence and low-level convergence circulations also provided vertical uplift for warm and moist air at the lower level;(4) Topography only played a minor role as the MCS developed and strengthened over relatively flat coastal terrain. Low level density flow induced by convection triggered new convective cell generation at the leading edge of the convective system, thereby playing a key role in the change of temperature gradient at lower layers, and resulting in strengthening atmospheric instability.

Role of the Subtropical Westerly Jet Waveguide in a Southern China Heavy Rainstorm in December 2013

An extreme rainstorm hit southern China during 13–17 December 2013, with a record-breaking daily rainfall rate, large spatial extent, and unusually long persistence. We examined what induced this heavy rainfall process, based on observed rainfall data and NCEP–NCAR reanalysis data through composite and diagnostic methods. The results showed that a Rossby waveguide within the subtropical westerly jet caused the event. The Rossby wave originated from strong cold air intrusion into the subtropical westerly jet over the eastern Mediterranean. With the enhancement and northward shift of the Middle East westerly jet, the Rossby wave propagated slowly eastward and deepened the India–Burma trough, which transported a large amount of moisture from the Bay of Bengal and South China Sea to southern China. Strong divergence in the upper troposphere, caused by the enhancement of the East Asian westerly jet, also favored the heavy rainfall process over Southeast China. In addition, the Rossby wave was associated with a negative-to-positive phase shift and enhancement of the North Atlantic Oscillation, but convergence in the eastern Mediterranean played the key role in the eastward propagation of the Rossby wave within the subtropical westerly jet.

Variational Data Assimilation Experiments of Mei-Yu Front Rainstorms in China

The numerical forecasts of mei-yu front rainstorms in China has been an important issue. The intensity and pattern of the frontal rainfall are greatly influenced by the initial fields of the numerical model. The 4-dimensional variational data assimilation technology (4DVAR) can effectively assimilate all kinds of observed data, including rainfall data at the observed stations, so that the initial fields and the precipitation forecast can both be greatly improved. The non-hydrostatic meso-scale model (MM5) and its adjoint model are used to study the development of the mei-yu front rainstorm from 1200 UTC 25 June to 0600 UTC 26 June 1999. By numerical simulation experiments and assimilation experiments, the T106 data and the observed 6-hour rainfall data are assimilated. The influences of many factors, such as the choice of the assimilated variables and the weighting coefficient, on the precipitation forecast results are studied. The numerical results show that 4DVAR is valuable and important to mei-yu front rainfall prediction.

Analysis on the Reason of Local Heavy Rainstorm Forecast Error in the Subtropical High Control

[Objective] The research aimed to study the reason of local heavy rainstorm forecast error in the subtropical high control. [Method] Started from summarizing the reason of forecast error, by using the conventional ground observation data, the upper air sounding data, T639, T213 and European Center (ECMWF) numerical prediction product data, GFS precipitation forecast product of U.S. National Center for Environmental Prediction, the weather situation, physical quantity field in a heavy rainstorm process which happened in the north of Shaoyang at night on August 5, 2010 were fully analyzed. Based on the numerical analysis forecast product data, the reason of heavy rainstorm forecast error in the subtropical high was comprehensively analyzed by using the comparison and analysis method of forecast and actual situation. [Result] The forecasters didn’t deeply and carefully analyze the weather situation. On the surface, 500 hPa was controlled by the subtropical high, but there was the weak shear line in 700 and 850 hPa. Moreover, they neglected the influences of weak cold air and easterlies wave. The subtropical high quickly weakened, and the system adjustment was too quick. The wind field variations in 850, 700 and 500 hPa which were forecasted by ECMWF had the big error with the actual situation. It was by east about 2 longitudes than the actual situation. In summer forecast, they only considered the intensity and position variations of 500 hPa subtropical high, and neglected the situation variations in the middle, low levels and on the ground. It was the most key element which caused the rainstorm forecast error in the subtropical high. The forecast error of numerical forecast products on the height field situation variation was big. The precipitation forecasts of Japan FSAS, U.S. National Center for Environmental Prediction GFS, T639 and T213 were all small. The humidity field forecast value of T639 was small. In the rainstorm forecast, the local rainstorm forecast index and method weren’t used in the forecast practice. In the precipitation forecast process, they only paid attention to the score prediction of station and didn’t value the non-site prediction. Some important physical quantity factors weren’t carefully studied. [Conclusion] The research provided the reference basis for the forecast and early warning of local heavy rainstorm.

Intermonthly Difference of Multi-attribute Characteristics of Rainstorm in China Based on Spatial-temporal Differentiation

Based on the daily precipitation data of 545 meteorological stations in China from 1961 to 2016, the spatial-temporal variation characteristics of rainstorm rainfall and rainy days in different months of China were diagnosed from three aspects: climatic characteristics, variation trend and interannual variation. The results showed that:(1) Rainstorm rainfall and rainy days in different months of China from 1961 to 2016 had similar spatial characteristics in corresponding months. From January to July, the high-value areas of rainstorm rainfall and rainy days gradually expanded from southeast coast to northwest inland, but mainly distributed in the east area of Hu Huanyong Line. From August to December, it shrank from northwest to southeast coastal areas. Rainstorm rainfall and rainy days were less distributed in different months in the west area of Hu Huanyong Line;(2) From 1961 to 2016, the spatial-temporal variation characteristics of rainstorm rainfall in different months in China were basically consistent with that of rainy days. May to August was the most significant month for the variation trend of rainstorm rainfall and rainy days in China. It mainly distributed in the southeast monsoon area, and was mainly increasing trend. The trend of rainstorm rainfall and rainy days in northwest China changed slightly in different months;(3) The interannual variability of rainstorm rainfall in different months in China from 1961 to 2016 was similar to that of rainy days. The fluctuation characteristics from April to October were larger in the northern region. The southern region fluctuated greatly from November to December in January to March. With the development of the month, the high-value areas with large daily fluctuations of rainstorm rainfall and rainy days gradually expanded from southeast to northwest, northeast and southwest, and the fluctuations in southeast tended to decrease, then shrank from northwest, northeast and southwest to southeast, with the increasing fluctuations in southeast. The study has certain reference significance for flood control and disaster reduction and water resources planning and utilization.

Study on Mesoscale Circulation Characteristics of Heavy Rainstorm in Wangmo County in Qianxinan on June 6,2011

[Objective] The aim was to analyze the causes of '6.06' heavy rainstorm in Wangmo County in Qianxinan.[Method] By dint of NCEP/NCAR 1°×1° reanalysis data,FY-2E TBB data,seven ground elements and two elements from automatic station data,the main influential system and all kinds of physical quantity field features of heavy rainstorm in upper reaches of Wangmo County in Qianxinan from the evening on 5 June to 08:00 on 6 June in 2011 were studied.[Result] The rainstorm was the result of cold air,which was provided by 850 hPa cold shear line and ground radiation line,and warm and wet airstream on the northwest edge of subtropical high.MCS was the main reason for such heavy rainstorm.Southwest warm and wet airstream in middle lower part provided sufficient water vapor for the rainstorm.The 850 hPa water vapor flux divergence center moved from north to south along ground convergence line to Qianxinan.Rainfall location and water vapor flux as well as convergence center were corresponding.The rainfall intensity also was consistent with the amount of water vapor flux and water vapor convergence.[Conclusion] The study provided reference for the report of heavy rainstorm.