ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 51,Issue 9,2025 Table of Contents
2025, 51(9):1029-1045.
DOI: 10.7519/j.issn.1000-0526.2025.041401
Abstract:
Due to the limitations of the limited area, lateral boundary perturbation is one of the primary perturbation methods for regional ensemble prediction. However, it remains unclear how to construct lateral boundary perturbations for the high-resolution regional ensemble prediction system of China Meteorological Administration (CMA) to improve forecast skill. This paper develops a mixed lateral boundary perturbation method using the perturbation field of the CMA global ensemble prediction and the lateral boundary field of the regional deterministic model, and also adjusts the perturbation magnitude through dynamic perturbation coefficients. The results show that no lateral boundary perturbation scheme can suppress the growth of perturbation energy at later forecast periods, leading to insufficient ensemble spreads. The mixed lateral boundary perturbation scheme can enhance the perturbation energy spectra at meso-α scale and large scale, and improve the spread-skill relationships and probabilistic forecast skills for isobaric elements and precipitation. Compared to the mixed lateral boundary perturbation scheme, the dynamic mixed lateral boundary perturbation scheme can enhance the spectral energy above 100 km and improve the spread-skill relationships and the probabilistic forecast skills for low-level variables and precipitation beyond 24 h. So, it has a good potential for operational application.
Due to the limitations of the limited area, lateral boundary perturbation is one of the primary perturbation methods for regional ensemble prediction. However, it remains unclear how to construct lateral boundary perturbations for the high-resolution regional ensemble prediction system of China Meteorological Administration (CMA) to improve forecast skill. This paper develops a mixed lateral boundary perturbation method using the perturbation field of the CMA global ensemble prediction and the lateral boundary field of the regional deterministic model, and also adjusts the perturbation magnitude through dynamic perturbation coefficients. The results show that no lateral boundary perturbation scheme can suppress the growth of perturbation energy at later forecast periods, leading to insufficient ensemble spreads. The mixed lateral boundary perturbation scheme can enhance the perturbation energy spectra at meso-α scale and large scale, and improve the spread-skill relationships and probabilistic forecast skills for isobaric elements and precipitation. Compared to the mixed lateral boundary perturbation scheme, the dynamic mixed lateral boundary perturbation scheme can enhance the spectral energy above 100 km and improve the spread-skill relationships and the probabilistic forecast skills for low-level variables and precipitation beyond 24 h. So, it has a good potential for operational application.
2025, 51(9):1046-1060.
DOI: 10.7519/j.issn.1000-0526.2025.041802
Abstract:
Based on the China Meteorological Administration (CMA) Convection-Permitting Ensemble Prediction System (CMA-CPEPS) and Regional Ensemble Prediction System (CMA-REPS), the precipitation forecast performance during the 2023 flood season (from 15 June to 28 August) in China, and a case analysis of the July 2023 extremely severe torrential rain in North China are objectively evaluated. The results indicate that CMA-REPS has the problem of systematically overestimating precipitation, but CMA-CPEPS can significantly overcome this problem. Relative to CMA-REPS, CMA-CPEPS shows the obvious superiority in prediction capacity for clear and rainy weather changes and its temporal changes, with a better probability forecasting and resolution ability for precipitation. Both CMA-CPEPS and CMA-REPS exhibit low spread values, while the spread/RMSE (root mean square error) value and the spatial correlation between spread and RMSE of CMA-CPEPS and CMA-REPS are equivalent. In the July 2023 extremely severe torrential rain in North China, CMA-CPEPS has a better ability to capture precipitation details compared to CMA-REPS. CMA-CPEPS outperforms CMA-REPS in forecasting precipitation intensity, evolution trend of precipitation intensity, and spatio-temporal resolution of heavy precipitation, especially in short-duration heavy precipitation events. Overall, CMA-CPEPS has a significantly enhancement over CMA-REPS in precipitation forecasting for the 2023 flood season in China.
Based on the China Meteorological Administration (CMA) Convection-Permitting Ensemble Prediction System (CMA-CPEPS) and Regional Ensemble Prediction System (CMA-REPS), the precipitation forecast performance during the 2023 flood season (from 15 June to 28 August) in China, and a case analysis of the July 2023 extremely severe torrential rain in North China are objectively evaluated. The results indicate that CMA-REPS has the problem of systematically overestimating precipitation, but CMA-CPEPS can significantly overcome this problem. Relative to CMA-REPS, CMA-CPEPS shows the obvious superiority in prediction capacity for clear and rainy weather changes and its temporal changes, with a better probability forecasting and resolution ability for precipitation. Both CMA-CPEPS and CMA-REPS exhibit low spread values, while the spread/RMSE (root mean square error) value and the spatial correlation between spread and RMSE of CMA-CPEPS and CMA-REPS are equivalent. In the July 2023 extremely severe torrential rain in North China, CMA-CPEPS has a better ability to capture precipitation details compared to CMA-REPS. CMA-CPEPS outperforms CMA-REPS in forecasting precipitation intensity, evolution trend of precipitation intensity, and spatio-temporal resolution of heavy precipitation, especially in short-duration heavy precipitation events. Overall, CMA-CPEPS has a significantly enhancement over CMA-REPS in precipitation forecasting for the 2023 flood season in China.
2025, 51(9):1061-1071.
DOI: 10.7519/j.issn.1000-0526.2025.031001
Abstract:
Based on conventional observation data, Doppler weather radar data and ERA5 reanalysis data, the physical process responsible for the enhancement and maintenance of a strong squall line affecting the Bohai Sea Area during the night of 31 July 2021 is analyzed. The results show that coastal terrain and sea surface temperature were the key factors for the intensity of squall lines. The warm water areas in the central and western Bohai Sea had favourable conditions for thermodynamic instability, and the areas with high wind speeds corresponded to the areas with high sea surface temperatures. The thermodynamic instability around Bohai Bay was the strongest, and the horn-shaped coastal terrain around Bohai Bay exhibited “the effect of funnelling”, resulting in significant wind field convergence on the windward side of the coast. This was conducive to triggering coastal convection. In the early stages, the cold pool outflow formed by multi-cell storms on land converged with environmental airflow, causing the storms to propagate eastward and move into the Bohai Bay. The uneven onshore wind caused by the complex coastal topography in the northern Bohai Bay was helpful for the rebirth of scattered thunderstorm cells along the coast, and the repeated incorporation of scattered thunderstorm cell made the onshore multi-cell storm continue to strengthen, forming a squall line.The herringbone squall line formed after entering the sea, accompanied by the merging of cold pools, and at the same time, a mesoscale vortex strengthened the squall line near the northern coastline of Bohai Bay. In the process of squall line strengthening at sea, the boundary layer frontogenesis associated with the warm water area and the cold pool played a critical role, finally making the squall line develop and strengthen in the warm water area of Bohai Sea but weaken and dissipate in the cold water area.
Based on conventional observation data, Doppler weather radar data and ERA5 reanalysis data, the physical process responsible for the enhancement and maintenance of a strong squall line affecting the Bohai Sea Area during the night of 31 July 2021 is analyzed. The results show that coastal terrain and sea surface temperature were the key factors for the intensity of squall lines. The warm water areas in the central and western Bohai Sea had favourable conditions for thermodynamic instability, and the areas with high wind speeds corresponded to the areas with high sea surface temperatures. The thermodynamic instability around Bohai Bay was the strongest, and the horn-shaped coastal terrain around Bohai Bay exhibited “the effect of funnelling”, resulting in significant wind field convergence on the windward side of the coast. This was conducive to triggering coastal convection. In the early stages, the cold pool outflow formed by multi-cell storms on land converged with environmental airflow, causing the storms to propagate eastward and move into the Bohai Bay. The uneven onshore wind caused by the complex coastal topography in the northern Bohai Bay was helpful for the rebirth of scattered thunderstorm cells along the coast, and the repeated incorporation of scattered thunderstorm cell made the onshore multi-cell storm continue to strengthen, forming a squall line.The herringbone squall line formed after entering the sea, accompanied by the merging of cold pools, and at the same time, a mesoscale vortex strengthened the squall line near the northern coastline of Bohai Bay. In the process of squall line strengthening at sea, the boundary layer frontogenesis associated with the warm water area and the cold pool played a critical role, finally making the squall line develop and strengthen in the warm water area of Bohai Sea but weaken and dissipate in the cold water area.
2025, 51(9):1072-1087.
DOI: 10.7519/j.issn.1000-0526.2025.012402
Abstract:
A warm-sector severe convective event dominated by short-time severe precipitation occurred in southern Anhui in the early morning of 27 May 2023. The train effect formed by a number of north-south parallel meso-β scale short convections resulted in 123.2 mm sudden local severe precipitation in 100 min. The numerical simulation of this event was carried out by using WRF-EnKF, a rapid update assimilation system for meteorological service operation in Anhui Meteorological Observatory. The results show that the interaction between large-scale environmental field and mesoscale convective system led to the increase of horizontal scale and intensification of several short convections. In terms of dynamic action, after the occurrence of convection, a meso-γ scale cyclonic vortex formed between the short convection and the low-level jet core, causing the development of eastward convection. Meanwhile, the surface convergence line formed between the outflow of thunderstorm and the ambient wind triggered new convection in the south side of the short convections, making the short convections continuously development linearly to the south. For the environmental conditions, multiple parallel low-level jet cores provided favorable dynamic and thermal conditions for the development of convection. Inverse secondary circulation in the middle and upper levels occurred due to the strong development of convections resulted in the significantly enhanced atmospheric instability on the south side and the development of convections strengthened the deep vertical wind shear. In addition, the interaction between the convections contributed to the maintenance of the short convection structure. Parallel convection formed parallel thunderstorm high pressure, and the interaction between the outflow of adjacent thunderstorms caused the formation of multiple parallel positive and negative divergence pairs, thus bringing about multiple parallel zonal-vertical circulations between adjacent convections in the vertical direction. These were conducive to the maintenance and development of the multiple short convections.
A warm-sector severe convective event dominated by short-time severe precipitation occurred in southern Anhui in the early morning of 27 May 2023. The train effect formed by a number of north-south parallel meso-β scale short convections resulted in 123.2 mm sudden local severe precipitation in 100 min. The numerical simulation of this event was carried out by using WRF-EnKF, a rapid update assimilation system for meteorological service operation in Anhui Meteorological Observatory. The results show that the interaction between large-scale environmental field and mesoscale convective system led to the increase of horizontal scale and intensification of several short convections. In terms of dynamic action, after the occurrence of convection, a meso-γ scale cyclonic vortex formed between the short convection and the low-level jet core, causing the development of eastward convection. Meanwhile, the surface convergence line formed between the outflow of thunderstorm and the ambient wind triggered new convection in the south side of the short convections, making the short convections continuously development linearly to the south. For the environmental conditions, multiple parallel low-level jet cores provided favorable dynamic and thermal conditions for the development of convection. Inverse secondary circulation in the middle and upper levels occurred due to the strong development of convections resulted in the significantly enhanced atmospheric instability on the south side and the development of convections strengthened the deep vertical wind shear. In addition, the interaction between the convections contributed to the maintenance of the short convection structure. Parallel convection formed parallel thunderstorm high pressure, and the interaction between the outflow of adjacent thunderstorms caused the formation of multiple parallel positive and negative divergence pairs, thus bringing about multiple parallel zonal-vertical circulations between adjacent convections in the vertical direction. These were conducive to the maintenance and development of the multiple short convections.
2025, 51(9):1088-1100.
DOI: 10.7519/j.issn.1000-0526.2025.031002
Abstract:
A localized severe convective rainfall event that occurred in east Sichuan Basin under the background of southwest vortex on 8 August 2021 is analyzed by using the Chongqing S-band dual-polarization radar data, ERA5 reanalysis data and multi-source precipitation product. The results show that at the early developing stage of the convection system, ZH and KDP began to increase. Snow particles played a major role in ice-phase hydrometers at middle-upper level. The proportion of drizzle identification at the low level ranged from 20% to 40%. Raindrops were small and surface hourly rainfall intensity was weak. During the rapid intensification of the convection system, ZH, ZDR and KDP increased rapidly as well. ZDR and KDP columns can extended well above 8 km. Uplifted droplets generated supercooled water, facilitating ice-phase process over the melting layer. The melting of descending ice hydrometeors led to the enhancement of liquid particles’ sizes and concentration at middle-lower level, which intensified the surface hourly rainfall intensity. Convective cells were merged with each other and shifted eastward subsequently. As the system weakened, dry and wet snow particles became the main components of ice-phase particles at middle-upper level again. Both size and number of liquid particles at middle-lower level decreased and surface hourly rainfall intensity got weakened accordingly. Dual-polarization variables and hydrometeor identification can basically reflect the characteristic of hydrometeor transformation within the convection systems and cohere reasonably with the variation of surface hourly rainfall intensity.
A localized severe convective rainfall event that occurred in east Sichuan Basin under the background of southwest vortex on 8 August 2021 is analyzed by using the Chongqing S-band dual-polarization radar data, ERA5 reanalysis data and multi-source precipitation product. The results show that at the early developing stage of the convection system, ZH and KDP began to increase. Snow particles played a major role in ice-phase hydrometers at middle-upper level. The proportion of drizzle identification at the low level ranged from 20% to 40%. Raindrops were small and surface hourly rainfall intensity was weak. During the rapid intensification of the convection system, ZH, ZDR and KDP increased rapidly as well. ZDR and KDP columns can extended well above 8 km. Uplifted droplets generated supercooled water, facilitating ice-phase process over the melting layer. The melting of descending ice hydrometeors led to the enhancement of liquid particles’ sizes and concentration at middle-lower level, which intensified the surface hourly rainfall intensity. Convective cells were merged with each other and shifted eastward subsequently. As the system weakened, dry and wet snow particles became the main components of ice-phase particles at middle-upper level again. Both size and number of liquid particles at middle-lower level decreased and surface hourly rainfall intensity got weakened accordingly. Dual-polarization variables and hydrometeor identification can basically reflect the characteristic of hydrometeor transformation within the convection systems and cohere reasonably with the variation of surface hourly rainfall intensity.
2025, 51(9):1101-1112.
DOI: 10.7519/j.issn.1000-0526.2024.123001
Abstract:
This study examines the multi-scale processes responsible for an extreme thunderstorm gale event (peak wind speed 31.5 m·s-1) that occurred at Tianjin Airport on 4 August 2013. The study focus is on the synoptic background, structural characteristics of the storm, and dynamical mechanisms of the extreme wind. The results show that this event developed within a post-trough unstable environment, characterized by a pronounced dry layer in the mid-troposphere and moisture concentration below 925 hPa. Convective available potential energy exceeding 3000 J·kg-1, coupled with strong 0-6 km vertical wind shear and steep temperature lapse rates in the boundary layer, established a favorable environment for thunderstorm gales. The damaging winds originated from a squall line propagating rapidly from northwest to southeast. The passage of its leading gust front triggered the initial wind surge, while subsequent extreme winds during the second phase resulted from a downburst generated by an intensifying multi-cell in the squall line. Both the squall line and downburst exhibited significant mobility, with precipitation-induced evaporative cooling, hydrometeor loading, and mid-level convergence identified as primary drivers for the downburst formation.
This study examines the multi-scale processes responsible for an extreme thunderstorm gale event (peak wind speed 31.5 m·s-1) that occurred at Tianjin Airport on 4 August 2013. The study focus is on the synoptic background, structural characteristics of the storm, and dynamical mechanisms of the extreme wind. The results show that this event developed within a post-trough unstable environment, characterized by a pronounced dry layer in the mid-troposphere and moisture concentration below 925 hPa. Convective available potential energy exceeding 3000 J·kg-1, coupled with strong 0-6 km vertical wind shear and steep temperature lapse rates in the boundary layer, established a favorable environment for thunderstorm gales. The damaging winds originated from a squall line propagating rapidly from northwest to southeast. The passage of its leading gust front triggered the initial wind surge, while subsequent extreme winds during the second phase resulted from a downburst generated by an intensifying multi-cell in the squall line. Both the squall line and downburst exhibited significant mobility, with precipitation-induced evaporative cooling, hydrometeor loading, and mid-level convergence identified as primary drivers for the downburst formation.
2025, 51(9):1113-1127.
DOI: 10.7519/j.issn.1000-0526.2025.011302
Abstract:
Based on the monthly reports of the maximum and minimum temperatures recorded by instruments since the establishment of the Guiyang National Reference Meteorological Station on 5 September 1920, the sequences of the maximum and minimum temperatures and the diurnal temperature ranges over the past century in Guiyang are established. Through multiple verification methods of the sequences, it has been found that the minimum temperature and the diurnal temperature ranges from 1938 to 1944 had significant differences from the mean value of the sequences, with breakpoints in the sequences appearing in 1937, 1944 and 2000. According to the historical evolution, observation record books and weather report stubs, as well as the comparison of multisource and multistation data, the minimum and maximum temperatures from 1938 to 1944 in the reports are found to be inaccurate, thus the data for this period are replaced with the records from the observation record books. Using the mean values of daily maximum and minimum temperatures and the daily temperature differences in 1938-1949, a conversion and correction scale is established to construct the daily temperatures for the period from 1921 to 1936 when temperature records are missing. The nonuniformity of temperature caused by station relocation is revised recursively by using the initial values of this station and the annual changes of the optimal reference station. The finally established homogenized temperature series of Guiyang over the past century shows a good consistency with the global temperature changes during the corresponding period. The results show that over the past century, the temperature in Guiyang has experienced two relatively significant “warming” stages, one from 1937 to 1953 and the other one since 1978. In the second warming stage, temperature rise was accelerated in 1996 and changed abruptly in 2011. The tendency rate of temperature change in Guiyang over the past century is 0.12℃ to 0.14℃ per decade, and the minimum temperature has been oscillating upward since 1929, warming up with a tendency rate of 0.26℃ to 0.31℃ per decade. The diurnal temperature ranges have been declining with a tendency rate of -0.29℃ to -0.27℃ per decade. There is no obvious trend variation in maximum temperature. The warming rates of temperature and minimum temperature in autumn and winter are higher than those in spring and summer. February is the month with warming, the most, while July is the month seeing warming, the least. The warming is mainly caused by the increase in minimum temperature.
Based on the monthly reports of the maximum and minimum temperatures recorded by instruments since the establishment of the Guiyang National Reference Meteorological Station on 5 September 1920, the sequences of the maximum and minimum temperatures and the diurnal temperature ranges over the past century in Guiyang are established. Through multiple verification methods of the sequences, it has been found that the minimum temperature and the diurnal temperature ranges from 1938 to 1944 had significant differences from the mean value of the sequences, with breakpoints in the sequences appearing in 1937, 1944 and 2000. According to the historical evolution, observation record books and weather report stubs, as well as the comparison of multisource and multistation data, the minimum and maximum temperatures from 1938 to 1944 in the reports are found to be inaccurate, thus the data for this period are replaced with the records from the observation record books. Using the mean values of daily maximum and minimum temperatures and the daily temperature differences in 1938-1949, a conversion and correction scale is established to construct the daily temperatures for the period from 1921 to 1936 when temperature records are missing. The nonuniformity of temperature caused by station relocation is revised recursively by using the initial values of this station and the annual changes of the optimal reference station. The finally established homogenized temperature series of Guiyang over the past century shows a good consistency with the global temperature changes during the corresponding period. The results show that over the past century, the temperature in Guiyang has experienced two relatively significant “warming” stages, one from 1937 to 1953 and the other one since 1978. In the second warming stage, temperature rise was accelerated in 1996 and changed abruptly in 2011. The tendency rate of temperature change in Guiyang over the past century is 0.12℃ to 0.14℃ per decade, and the minimum temperature has been oscillating upward since 1929, warming up with a tendency rate of 0.26℃ to 0.31℃ per decade. The diurnal temperature ranges have been declining with a tendency rate of -0.29℃ to -0.27℃ per decade. There is no obvious trend variation in maximum temperature. The warming rates of temperature and minimum temperature in autumn and winter are higher than those in spring and summer. February is the month with warming, the most, while July is the month seeing warming, the least. The warming is mainly caused by the increase in minimum temperature.
2025, 51(9):1128-1136.
DOI: 10.7519/j.issn.1000-0526.2025.040601
Abstract:
Based on observation data and ballistic trajectory theory, a simple model is established to analyze the influence of atmospheric vertical structure on the weather modification rocket ballistic trajectory during the ascending phase of rockets. The results indicate that the strength and direction of the horizontal wind field have significant impact on ballistic trajectory, especially in low-level wind fields below 1000 m height. The impact of air density is relatively small. The model could be beneficial for ballistic correction, includ-ing ballistic height, deflection, and distance, and would provide relatively accurate prediction trajectory for weather modification rocket.
Based on observation data and ballistic trajectory theory, a simple model is established to analyze the influence of atmospheric vertical structure on the weather modification rocket ballistic trajectory during the ascending phase of rockets. The results indicate that the strength and direction of the horizontal wind field have significant impact on ballistic trajectory, especially in low-level wind fields below 1000 m height. The impact of air density is relatively small. The model could be beneficial for ballistic correction, includ-ing ballistic height, deflection, and distance, and would provide relatively accurate prediction trajectory for weather modification rocket.
2025, 51(9):1137-1145.
DOI: 10.7519/j.issn.1000-0526.2025.011001
Abstract:
To obtain the X-band dual-polarization radar characteristics of hail in southwestern Yunnan, a statistical analysis method is used to analyze 22 hail sample data detected by the Menglian X-Band Dual-Polarization Radar. The results show that hailstorm cells have maximum horizontal reflectivity factor (ZH) ≥58 dBz, 45 dBz echo height (H45) ≥7.1 km, with a height difference between H45 and the wet-bulb 0℃ level being ≥3.3 km. H45 above 86% of hail cells have exceeding the height of the -20℃ layer. 50 dBz echo height (H50) is ≥5.7 km, with a height difference between H50 and the -20℃ level ranging from -1.2 km to 2.7 km. Vertical integrated liquid water content (VIL) density is ≥2.8 g·m-3, and the VIL is increased by 4.7-18.3 kg·m-2 in the volume scan preceding hailfall. When differential reflectivity (ZDR) and specific differential phase (KDP) average and median values are above 0℃ layer, they are concentrated near the value of 0 dB and 0 °·km-1, predominantly being negative. Below 0℃ layer within 1 km, they change from negative to positive values, gradually increasing with the height decrease. The maximum values appear in the near-surface layer, reaching approximately 1.5 dB and 0.7 °·km-1 respectively. The ranges of values for parameters above the 0℃ layer are: ZDR from -1.92 dB to 1.35 dB, KDP from -1.97 °·km-1 to 1.29 °·km-1, and correlation coefficient (CC) from 0.86 to 0.99, while below the 0℃ layer, ZDR from -1.92 dB to 3.74 dB, KDP from -2.98 °·km-1 to 2.66 °·km-1, and CC from 0.79 to 0.98. The research results could be a reference for the detection and identification of hail characteristics by the X-band dual-polarization radar in the southwestern Yunnan Region.
To obtain the X-band dual-polarization radar characteristics of hail in southwestern Yunnan, a statistical analysis method is used to analyze 22 hail sample data detected by the Menglian X-Band Dual-Polarization Radar. The results show that hailstorm cells have maximum horizontal reflectivity factor (ZH) ≥58 dBz, 45 dBz echo height (H45) ≥7.1 km, with a height difference between H45 and the wet-bulb 0℃ level being ≥3.3 km. H45 above 86% of hail cells have exceeding the height of the -20℃ layer. 50 dBz echo height (H50) is ≥5.7 km, with a height difference between H50 and the -20℃ level ranging from -1.2 km to 2.7 km. Vertical integrated liquid water content (VIL) density is ≥2.8 g·m-3, and the VIL is increased by 4.7-18.3 kg·m-2 in the volume scan preceding hailfall. When differential reflectivity (ZDR) and specific differential phase (KDP) average and median values are above 0℃ layer, they are concentrated near the value of 0 dB and 0 °·km-1, predominantly being negative. Below 0℃ layer within 1 km, they change from negative to positive values, gradually increasing with the height decrease. The maximum values appear in the near-surface layer, reaching approximately 1.5 dB and 0.7 °·km-1 respectively. The ranges of values for parameters above the 0℃ layer are: ZDR from -1.92 dB to 1.35 dB, KDP from -1.97 °·km-1 to 1.29 °·km-1, and correlation coefficient (CC) from 0.86 to 0.99, while below the 0℃ layer, ZDR from -1.92 dB to 3.74 dB, KDP from -2.98 °·km-1 to 2.66 °·km-1, and CC from 0.79 to 0.98. The research results could be a reference for the detection and identification of hail characteristics by the X-band dual-polarization radar in the southwestern Yunnan Region.
2025, 51(9):1146-1156.
DOI: 10.7519/j.issn.1000-0526.2025.082701
Abstract:
The main characteristics of the general circulation of atmosphere in June 2025 are as follows. The Northern Hemisphere midtohigh latitude circulation exhibited a multiwave pattern. The region from the West Siberian Plain to northwestern China remained dominated by the average highpressure ridge and persistent positive height field anomalies. Meanwhile, the subtropical high showed a significant westward and northward displacement with intensified strength. The monthly mean temperature across China was 21.3℃, exceeding the climatological average (20.4℃) by 0.9℃ and being ranked as the secondhighest since 1961. The number of high temperature days was 3.3 days, surpassing the norm of 1.7 days. The monthly average precipitation reached 106.2 mm across China, 3.3% above the climatological mean (102.8 mm). The Meiyu season commenced early, with significantly more precipitation in the middle and lower reaches of the Yangtze River. During the month, there were two typhoons generated, but their genesis time was strikingly late with the first landfall striking early. Concurrently, there occurred six torrential rain episodes, five prolonged heatwaves, five severe convective weather events, and precipitating extreme weather events across multiple regions. Moreover, this paper briefly analyzes the basic causes and forecasting challenges related to the torrential rain induced by the first Typhoon Wutip, and the extreme heavy precipitation episode from Guizhou to the middle and lower reaches of the Yangtze River during 17-23 June.
The main characteristics of the general circulation of atmosphere in June 2025 are as follows. The Northern Hemisphere midtohigh latitude circulation exhibited a multiwave pattern. The region from the West Siberian Plain to northwestern China remained dominated by the average highpressure ridge and persistent positive height field anomalies. Meanwhile, the subtropical high showed a significant westward and northward displacement with intensified strength. The monthly mean temperature across China was 21.3℃, exceeding the climatological average (20.4℃) by 0.9℃ and being ranked as the secondhighest since 1961. The number of high temperature days was 3.3 days, surpassing the norm of 1.7 days. The monthly average precipitation reached 106.2 mm across China, 3.3% above the climatological mean (102.8 mm). The Meiyu season commenced early, with significantly more precipitation in the middle and lower reaches of the Yangtze River. During the month, there were two typhoons generated, but their genesis time was strikingly late with the first landfall striking early. Concurrently, there occurred six torrential rain episodes, five prolonged heatwaves, five severe convective weather events, and precipitating extreme weather events across multiple regions. Moreover, this paper briefly analyzes the basic causes and forecasting challenges related to the torrential rain induced by the first Typhoon Wutip, and the extreme heavy precipitation episode from Guizhou to the middle and lower reaches of the Yangtze River during 17-23 June.
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ISSN:1000-0526 CN:11-2282/P