The aim of this session is to gain an improved understanding of mesoscale and severe convective processes over land from a non-idealised perspective for current and future periods.
We invite contributions focussing on the underlying storm dynamics and microphysics, upscale effects, advances in modelling and predictability of these storm systems, and their impacts. We also invite contributions on the driving processes of the formation and evolution of severe convection, and how these factors explain spatio-temporal patterns of storm intensity, precipitation, and on-the-ground hazards. This includes contributions on land-convection interactions in connection with mesoscale and severe storms, e.g. effects of complex topography, soil moisture feedbacks, or land use / land use change including e.g. urbanisation, deforestation, or irrigation.
Contributions focussing on individual extreme events or giving climatological perspectives including future climates are welcome, as are studies relying on remote sensing data, in-situ observations, or high-resolution models, especially those that explicitly resolve convection.
Using high-resolution observations, mesoscale simulations, and idealized experiments, this study investigates the mechanisms governing an episode of orographic convection initiation (CI) during the North China Heavy Rainfall Experiment. On 4 August 2024, repeated CI occurred over the eastern slopes of Taihang Mountains in the late afternoon, subsequently enhancing an upstream downhill convective storm. Wind profiler radar data and dense automatic weather stations reveal that CI was supported by strengthening southeasterly upslope winds. These winds primarily resulted from the migration of the mountain-plain solenoid and the mountainward-propagating outflow from a convective cold pool over the plain, with sensitivity experiments showing the latter contributed roughly 22% of the wind strength. The upslope flows gradually transported unstable air from the plain to the slope, fostering CI. Mesoscale simulations further highlight the key role of orographic waves near the mountain ridge, which generated strong downslope winds. The near-surface convergence between downslope and upslope flows, combined with wave-induced divergence aloft, produced deep ascent over the slope. Removing mountain ridges weakened wave strength and reduced downslope wind speeds by ~8 m s⁻¹.Without orographic heating in the idealized simulation (i.e., no mountain-plain solenoid), only strong wave descent occurred below 2 km, inhibiting CI. These findings underscore the critical interplay among plain convection, orographic waves, and the mountain-plain solenoid, offering new insight into the processes controlling orographic CI in North China.
How to cite: Du, Y., Yang, H., Chen, Z., and Gao, X.: Convection Initiation over Mountain Slopes in North China: Roles of Upslope Winds and Orographic Waves, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15275, https://doi.org/10.5194/egusphere-egu26-15275, 2026.
The global expansion of green renewable energy in recent decades has led to a substantial increase in the number of wind farms. While the long-term impacts of wind farms on the atmosphere have been the subject of some research, their short-term effects on weather phenomena, such as convection initiation (CI), remain insufficiently understood. This study addresses this gap by exploring the influence of wind farms on CI, contributing to a broader understanding of anthropogenic impacts on natural atmospheric processes. We explored the general features of CI events from June−August during 2021–2023 associated with desert wind farms in Inner Mongolia, China. A total of 72 CI events were identified with 24% associated with the boundary layer convergence line (BLCL) generated due to desert-oasis vegetation contrast. The impact of the wind farms on the CI process embedded in stratiform cloud on 12 July 2022 from DEsert-oasis COnvergence line and Deep convection Experiment was examined through simulations using Weather Research and Forecasting (WRF) model. Results showed that wind farms can accelerate CI by intensifying the BLCL and shift it southward. It was found that wind farms generated upward-propagating gravity waves, which modulated water vapor transport and led to a reduction in moisture content within the stratiform cloud layer, thereby decreasing cloud coverage and thus increasing solar radiation and surface temperature. The modified surface temperature distribution then shifted the BLCL southward and intensifying it, which eventually accelerated CI.
How to cite: Meng, Z., Cui, Q., Wang, C., Liu, H., Zheng, Z., and Wang, X.: Impact of Desert Wind Farms on Convection Initiation , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-234, https://doi.org/10.5194/egusphere-egu26-234, 2026.
An EF1 tornado was documented using photographs, a high-resolution video, and a mobile radar as it entered Selden, Kansas, on 24 May 2021. The kinematic structure of the tornadic wind field was presented by tracking lofted debris and analyzing single-Doppler velocities. Tracking of debris on the side of the tornado farthest from the observer was possible due to the transparent nature of the debris cloud. The analysis suggests that the circulation was axisymmetric with the maximum horizontal velocities located at low levels. The positive vertical velocities were strongest on the forward side of the tornado. The maximum vertical velocities were associated with a secondary vortex. For the first time, the dataset provided an opportunity to assess the orientation of a large, lofted debris based on the images recorded by a movie and compare these observations with the differential radar reflectivity (ZDR) recorded by a mobile polarimetric radar. The T-matrix calculations of wood boards yielded a mean ZDR that was negative and was also observed in the ZDR analysis suggesting a preference for lofted debris to be vertically oriented.
How to cite: Wakimoto, R.: Structure of a Tornado Based on an Analysis of Lofted Debris Speeds, Debris Orientation, and Mobile Radar Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1599, https://doi.org/10.5194/egusphere-egu26-1599, 2026.
Hail is a leading source of insured losses globally, but the occurrence of damaging hail in tropical regions is subject to large uncertainty. In the tropics globally, satellite-based hail detection often detects the presence of ice aloft, and hail proxies frequently show hail-prone conditions driven by high convective instability. However, high melting rates in these warm regions may modulate the amount of hail reaching the surface, and it is therefore often assumed that satellite-based methods overestimate hail occurrence in the tropics. The extent to which damaging (> 2 cm) hail reaches the surface in these warm regions is not well quantified, owing to a sparsity of observational records in many tropical regions. Here, we used high-resolution numerical weather simulations in an ensemble setup with varying microphysics schemes to examine the plausibility of damaging surface hail occurrence, for satellite-detected hailstorms in Australia's tropics. The simulations explicitly estimated hailstone size at the surface using a column model for hail growth and melt. The results show that a significant subset of the cases could plausibly have produced damaging hail at the surface, with cases with simulated surface hail exhibiting greater mid-to-upper level moisture and higher instability than cases without hail. These results may help improve process understanding for hail in the tropics worldwide.
How to cite: Raupach, T., Bang, S., and Allen, J.: Simulations of satellite-detected hailstorms to examine damaging hail occurrence in Australia's tropics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5998, https://doi.org/10.5194/egusphere-egu26-5998, 2026.
Subtropical highs are large-scale dominant weather systems with significant impacts on regional climate and weather patterns. However, their cross-scale influence on mesoscale convective systems (MCSs) remains insufficiently understood. This study investigates how satellite-observed MCS characteristics vary with the western Pacific subtropical high (WPSH) over southeastern mainland China (SEMC), where the WPSH exerts a most frequent influence within the Asian continent. In 7-yr warm seasons, 725 WPSH days were identified and objectively classified into distinct weather types categorized as either WPSH-periphery or WPSH-center patterns, based on SEMC’s location relative to the WPSH. Although MCSs are generally less frequent in the WPSH-center patterns than in the WPSH-periphery ones, their occurrence remains noteworthy near regional hotspots. Across all patterns, MCS occurrence consistently exhibits a diurnal peak in late afternoon and early evening. The WPSH-center patterns show a larger diurnal amplitude with more intensive MCS activity around this peak period. MCSs in the WPSH-center patterns tend to have shorter lifetimes, fewer merging/splitting processes, and a greater tendency to form locally over SEMC in the afternoon. Despite varying movement directions and orientations, MCSs across different patterns generally move along their orientation to facilitate the MCS “training” effect, especially in the WPSH-center patterns due to slower moving speeds and stronger intensities. The analysis on atmospheric conditions suggests that MCS occurrence in the WPSH-periphery patterns is more closely linked to synoptic disturbances, including enhanced moisture transport via low-level jet streams and midlevel upward motion. The convective parameters including convective available potential energy (CAPE), total column water, and K index effectively differentiate MCS-active days from MCS-inactive days for each WPSH pattern.
How to cite: Huang, Y. and Zhang, M.: Satellite-Based Characterization of Warm-Season Mesoscale Convective Systems over Southeastern Mainland China in Response to the Western Pacific Subtropical High, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2408, https://doi.org/10.5194/egusphere-egu26-2408, 2026.
Mesoscale convective systems (MCSs) play a central role in regulating the global energy and water cycles through their extensive cloud coverage and the associated redistribution of latent heat. Global convection-permitting models at kilometer scale have made substantial progress in representing several MCS characteristics, including bulk precipitation statistics and anvil extent. However, persistent deficiencies remain in simulating MCS populations in key tropical hotspots. Using four years of global ICON simulations at 2.5 km horizontal resolution, we identify systematic regional biases in MCS occurrence, with overestimated MCS initiation over the Amazon and Congo forest regions. In addition, simulated MCSs generally have less spatial extent than those identified in satellite-based observations.
In this talk, we investigate the physical drivers underlying these biases using causal machine learning approaches to identify environmental factors that control MCS initiation, size, and intensity. Preliminary observational analyses indicate that, over the Amazon basin, mid-level wind shear and column-integrated water vapor exert strong controls on MCS size and total precipitation. We compare these observed causal relationships with those inferred from the ICON simulations to assess whether the same controlling factors operate in the model. Discrepancies in the identified drivers provide insight into the mechanisms responsible for model biases, their impacts on simulated MCS structure and rainfall characteristics, and potential pathways on how to improve the modeling system.
How to cite: Wang, D., Prein, A., Zeman, C., and Pothapakula, P.: Causal Drivers of Continental Mesoscale Convective System Biases in Kilometer-Scale Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10770, https://doi.org/10.5194/egusphere-egu26-10770, 2026.
Accurate simulation of extreme precipitation remains a major challenge for weather prediction. Even in convection-permitting simulations at kilometer-scale resolution, biases such as underestimation of light rainfall frequency, overestimation of heavy rainfall events, and poor representation of localized convective extremes persist. These deficiencies are partly attributed to under-resolved lateral mixing between intense convective updrafts and their surrounding environment. Recently developed rotational mixing framework [1], which apply rotation to the convective-scale flow to enhance sub-grid-scale lateral mixing without artificially strengthening updrafts or downdrafts showed promising improvement for a month-long simulation. However, its applicability to moisture-rich convective environment of the tropics, particularly for short-duration, high-impact extreme rainfall events, has not yet been assessed. This study evaluates this rotational framework over India during monsoon in convection-permitting 4 km Weather Research and Forecasting (WRF) model simulations for five high-impact extreme rainfall events: Mumbai (July 2019), Kerala (August 2019), Delhi (July 2023), Gujarat (August 2024), and Andhra Pradesh (September 2024). We apply a 10° rotation (ROTMIX10) to the convective-scale flow to enhance sub-grid-scale lateral mixing while preserving the dynamical integrity of convective updrafts and downdrafts. We evaluate the model performance using the GPM precipitation and brightness temperature estimates. For each case, we compare the simulations using the ROTMIX10 framework against a standard CONTROL (no rotation) configuration. Across all cases, ROTMIX10 consistently improves the simulation of extreme precipitation, more accurately capturing rainfall intensities (RMSE reduced from 25.83 to 25.18) and enhancing spatial coherence of convective cores (correlation coefficient increasing from 0.42 to 0.51). Forecast skill also improves substantially, with the probability of detection rising from 0.20 to 0.37. We also find that these extreme events are primarily associated with mesoscale convective systems (MCSs), whose lifetimes, spatial extents, convective intensities, and accumulated rainfalls are more realistically represented in the ROTMIX10 simulations. Analysis of the underlying physical processes reveals that rotational mixing broadens the vertical velocity spectrum and enhances detrainment of moisture and condensate from strong updrafts between 4 and 12 km, moistening the mid-troposphere and increasing condensate loading in downdraft regions. This preconditions the atmosphere for subsequent convection, allowing rainfall to initiate under relatively drier conditions. Additionally, ROTMIX10 mitigates the typical bias of excessively cold cloud tops, yielding brightness temperature and reflectivity distributions closer to satellite observations. Overall, this work provides the first investigation of the performance of the rotational mixing framework for simulating high-impact convective extremes in the tropics. This approach demonstrates that rotational mixing framework enhances the physical realism of convective processes and improves extreme precipitation statistics in convection-permitting models.
[1] Hagos, S., Feng, Z., Varble, A. C., Tai, S. L., & Chen, J. (2025). The impacts of rotational mixing on the precipitation simulated by a convection permitting model. Journal of Advances in Modeling Earth Systems, 17(5), e2024MS004524.
How to cite: Paul, D., Dubey, S., Mukhopadhyay, P., and Hagos, S.: Improving the Simulations of Indian Extreme Precipitation Events through a Rotational Mixing Framework in the WRF Model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10202, https://doi.org/10.5194/egusphere-egu26-10202, 2026.
Supercell thunderstorms are among the most hazardous convective storms in Europe, yet their climatology and environmental conditions are poorly constrained. Using km-scale climate simulations, we present a pan-European supercell climatology for the current climate and assess changes in a +3 °C global warming scenario. Supercells preferentially occur near mountain ranges, with a pronounced maximum over northern Italy and the southern Alps. In the warmer climate, supercell frequency increases by 11% and shifts northeastward and toward higher elevations, while decreases over southwestern Europe are linked to regional drying.
Supercells occur in environments with enhanced instability and deep-layer shear. The storm population splits into 87% right-moving (RM) supercells and 13% left-moving (LM). RMs exhibit more coherent structures and larger high-intensity areas than LMs, while LMs occur in a narrower range of warmer, drier and less stable environments. In the warmer climate, greater instability and increased shear lead to stronger hazards, including hail, lightning and intense precipitation, with hazard and frequency increases being particularly pronounced for LMs.
These results highlight robust changes in European supercell occurrence and associated hazards in a changing climate.
How to cite: Feldmann, M., Beer, S., Blanc, M., Zeeb, A., Brennan, K., Thurnherr, I., Wilhelm, L., Schär, C., and Martius, O.: Supercell thunderstorms in Europe - climatology, morphology and climate change , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20771, https://doi.org/10.5194/egusphere-egu26-20771, 2026.
A number of recent catastrophic floods (e.g., Valencia, Spain) were driven by heavy, persistent rainfall from mesoscale convective systems (MCSs), which are major contributors to extreme precipitation in Europe. Understanding how MCS rainfall responds to warming is therefore critical for assessing future flood risk. Extreme rainfall depends not only on instantaneous intensity but also on the persistence and spatial organization of precipitation. MCSs are typically a blend of intense, localized regions of “convective” precipitation alongside broader, less intense areas of “stratiform” precipitation. While extremes of both components are expected to intensify according to the Clausius-Clapeyron (CC) relationship (Da Silva & Haerter, 2025), flood-relevant rainfall additionally depends on changes in convective cluster size, number, spatial distribution, and system-scale organization.
Here, we use observational data to quantify how MCS properties scale with surface temperature in the present climate over Germany. MCSs are identified and tracked using radar precipitation and lightning observations, and convective rainfall is separated from stratiform rainfall using two independent detection methods. We examine the changes in convective cluster number, size, spatial aggregation, and system-scale characteristics with near-surface temperature.
We find that, with increasing temperature, convective clusters within MCSs become more numerous and larger, while also more spatially dispersed. Convective rainfall, typically concentrated on the southern flank of MCSs, increasingly extends northward under warmer conditions, consistent with enhanced convective instability on the northern side and slightly reduced vertical wind shear. In contrast, total MCS area, propagation speed, and convective persistence show no systematic temperature dependence.
A statistical model reproducing these temperature-dependent changes indicates that CC-driven increases in pointwise convective intensity dominate the scaling of area-averaged rainfall, explaining ~80% of the increase at mesoscale (10–100 km) scales. Increases in convective cluster size and number contribute ~20% each, while enhanced spatial dispersion partially offsets these effects (~20%).
These results constrain current-day temperature-dependent rainfall scaling and may aid the interpretation of projected extreme precipitation changes.
Da Silva, Nicolas A., and Jan O. Haerter. "Super-Clausius–Clapeyron scaling of extreme precipitation explained by shift from stratiform to convective rain type." Nature Geoscience (2025).
How to cite: Da Silva, N. and Haerter, J.: More intense and more dispersed convective cell clusters in European MCSs under higher temperatures, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19950, https://doi.org/10.5194/egusphere-egu26-19950, 2026.
One of the important problems in atmospheric physics that has remained unresolved to the present time is the problem of the formation and evolution of tornado-like vortices near the surface.
In the present work, the process of formation and evolution of tornado-like vortices near the surface is investigated as a result of the evolution of a long-lived vortex formed at some altitude under thunderstorm cloud conditions.
A two-dimensional axisymmetric model is considered, in which the initial vorticity is maintained by an external force. The influence of the temperature field on the evolution of vorticity near the surface is examined. It is found that at relatively short times, the behavior of the forming tornado-like vortices near the surface is universal and only weakly dependent on the external force and the temperature field. Nevertheless, with time, their influence becomes significant. It is shown that an anomaly in the vertical temperature distribution leads to the result that a tornado-like vortex formed near the surface can exist for a long time.
How to cite: Golbraikh, E. and Elikashvili, A.: The connection between the long-lived initial vortex aloft and the tornado near the surface., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2119, https://doi.org/10.5194/egusphere-egu26-2119, 2026.
The Qinghai-Tibet Plateau (TP), the world's highest and most complex plateau, serves as a critical gateway for tropospheric substances entering the stratosphere. Northwestern South Asia, particularly the region encompassing the steep terrain of the westernmost indentation between the TP and the Iranian Plateau, is a global hotspot for frequent and energetic convective storms. Therefore, it is vital to investigate how these thunderstorms impact the atmospheric composition over the pristine TP, especially for short-lived species. Using TRMM satellite observations (1998-2013), ERA-5 reanalysis data, and the HYSPLIT trajectory model, this study comprehensively examines the transport mechanisms associated with these storms. Our findings reveal that thunderstorms predominantly occur during the SASM and are concentrated along the southern Himalayan front. By employing the HYSPLIT model to trace transport pathways associated with the thunderstorm, the study demonstrates a clear convergence of pollutants from the South Asia boundary layer into thunderclouds. Furthermore, we identify three principal transport pathways for substances from thunderstorm tops into the TP atmosphere, closely linked to larger-scale circulations: (1) the tropospheric westerlies (~58% of cases), (2) the anticyclonic circulation of the South Asian High (~33%), and (3) tropopause-penetrating processes (~9%). These results clarify the mechanisms—primarily associated with westerlies and the South Asian High—through which intense South Asian thunderstorms influence the TP. The impact of this thunderstorm-driven transport on the TP and the lower stratosphere is projected to intensify with increasing thunderstorm frequency and pollution levels in South Asia under global warming and continued local development.
How to cite: Wu, X., Li, X., Qie, X., Hu, Y., and Zhang, Z.: Mechanisms and Impacts of South Asian Thunderstorm-Driven Transport on the Atmospheric Composition over the Tibetan Plateau and Stratosphere, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2415, https://doi.org/10.5194/egusphere-egu26-2415, 2026.
On 18–19 June 2018, the metropolitan area of Abidjan in Côte d’Ivoire experienced one of the most extreme daily rainfall events in its observational history with 302 mm within 24 hours. With severe urban flooding, at least 20 fatalities, and substantial economic losses, this event underscore serious knowledge gaps about extreme rainfall processes along the West African coast. In particular, the mechanisms leading to highly localized, sub-daily rainfall extremes in the humid environment of the Guinea Coast region remain insufficiently understood. At the same time, such events are difficult to anticipate with current numerical weather prediction systems which limits the effectiveness of early warning. These challenges motivated a focused process-oriented case study of the extreme June 2018 Abidjan rainfall event.
Leveraging multi-source observational datasets combining unique, largely non-public, sub-daily to daily rain gauge measurements over the District of Abidjan, satellite-based IMERG precipitation and METEOSAT cloud observations, the extremeness of the event and the temporal evolution of the responsible mesoscale convective system (MCS) was investigated. Large-scale and mesoscale environmental conditions, including moisture, flow patterns, and vorticity tendencies, were characterized with the ECMWF’s reanalysis product ERA5. Finally, with the aim of assessing how well a state-of-the-art global prediction system captures the likelihood and timing of an extreme rainfall event over West Africa, forecast performance and practical predictability were evaluated using ensemble predictions from the ECMWF Integrated Forecasting System.
The present analysis reveals several aspects that characterize the June 2018 Abidjan extreme rainfall event.
- First, rain gauge observations show that the locally recorded total of 302 mm within 24 hours ranks among the most extreme daily rainfall amounts documented along the Ivorian coast while surrounding stations simultaneously experienced widespread totals above 100 mm. This highlights the combined localized and regional nature of the event.
- Second, satellite-based cloud tracking indicates that the extreme rainfall was associated with a long-lived, westward-propagating MCS, whose convective signatures weakened as it approached Abidjan, but yet continued to produce exceptional rainfall accumulations within a moisture-rich coastal environment.
- Third, the event was marked by the development of a pronounced moist low-tropospheric vortex over the Abidjan area, accompanied by unusually strong moisture flux convergence and extreme column-integrated water vapor. A vorticity budget analysis suggests that vortex intensification was supported by tilting and the divergence term which underlines the hypothesis of an active MCS-vortex interaction during the extreme event.
- Finally, evaluating the Extreme Forecast Index, enhanced likelihood of extreme rainfall over Abidjan was only indicated at short lead times where ensemble-based extreme precipitation signals emerging not before 12 hours before onset. This showcases substantial limitations in the current predictability of such events over West Africa.
This study suggests that future work should explore the climatology of such moist vortices, their representation in convection-permitting and global models, and their potential as predictors for extreme West African rainfall in ensemble-based and data-driven forecasting approaches. Advancing these directions holds promise for enhancing early warning capabilities at operational prediction centers and reducing flood risk in rapidly growing coastal cities of West Africa.
How to cite: Maranan, M., Touré, I. S., Fink, A. H., Kouadio, K., Yoroba, F., Touré, E., Kobea, A., and Diedhiou, A.: Mesoscale Convective System Development, Synoptic Drivers, and Forecast Challenges of a Catastrophic Coastal Rainfall Event in West Africa, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15148, https://doi.org/10.5194/egusphere-egu26-15148, 2026.
Macau, owing to its unique geographical location, experiences complex and highly variable weather conditions and is frequently affected by heavy rainfall during the flood season. To comprehensively investigate the environmental conditions and characteristics of heavy rainfall events in Macau, this study identifies heavy rainfall events occurring from 2014 to 2023 using multi-source observational and reanalysis data and classifies them according to weather patterns, for subsequent environment and radar-echo analysis. The annual, monthly and categorical distributions indicate that heavy rainfall events predominantly occur between May and October. Among the classified types, tropical-cyclone (TC) and warm-sector (WS) events are the most frequent overall. WS, frontal (FT), and low-vortex shear (LS) events occur more frequently during the pre-flood season (May ~ July), whereas TC and southeast wind (SW) events dominate in the post-flood season (August ~ October). Analyses of key environmental parameters reveal that LS and WS events are characterized by stronger thermodynamic instability, whereas SW and TC events generally exhibit more favorable moisture conditions throughout the atmospheric column and in the lower troposphere. Despite similar moisture-rich environments, SW and TC events differ in terms of moisture replenishment capability and near-surface moisture conditions. Radar echoes of each associated with different heavy rainfall types exhibit distinct characteristics in terms of mobility, initiation, centroid height and echo intensity. Statistical results indicate that WS and LS events tend to have lower centroid heights and relatively stronger echo intensities, whereas FT and SW echoes generally exhibit higher centroid heights, with SW echoes being weaker in intensity. In contrast, TC echoes are associated with relatively lower centroid heights, with echo intensity spanning a wide range from strong to weak. Furthermore, dual-polarization parameter analysis further reveals that WS and LS events frequently exhibit a column on the upstream side and a column on the downstream side, indicating relatively larger raindrop sizes and higher particle concentrations over Macau. In contrast, TC and SW echoes over Macau are generally characterized by lower values but higher values, implying smaller raindrop sizes accompanied by higher particle concentrations.
How to cite: Wang, D. and Zeng, Q.: A Study on Heavy Rainfall Environments and Radar Echoes in Macau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15603, https://doi.org/10.5194/egusphere-egu26-15603, 2026.
During summer over the Korean Peninsula, a nocturnal low-level jet (LLJ) frequently develops and induces strong low-level convergence, which can initiate elevated convection above the planetary boundary layer and result in localized heavy rainfall. Because near-surface divergence/convergence signals are often weak, such events are difficult to anticipate and may produce intense precipitation over short time scales, leading to substantial societal impacts. In this study, we analyze an LLJ-related heavy rainfall event on 3 August 2022 using the Weather Research and Forecasting (WRF) model, with emphasis on the development mechanisms and simulation characteristics. The thermodynamic environment was evaluated using equivalent potential temperature, the level of free convection (LFC), and the presence of a moist absolutely unstable layer (MAUL). We further examined the roles of topography and model resolution by conducting terrain-sensitivity experiments and by comparing a convection-permitting simulation with a large-eddy simulation (LES). The simulations indicate that, under synoptic conditions characterized by a remnant tropical-depression circulation and inflow along the periphery of a high-pressure system, the LLJ enhanced moisture transport and focused low-level convergence into the central inland region. Diagnostics of the relative configuration between the maximum equivalent potential temperature height and the LFC, together with MAUL identification, support that the event occurred in a standard elevated-convection environment. The sensitivity experiment with reduced terrain height indicates that terrain enhances LLJ-related convergence and associated heavy precipitation, suggesting that the complex topography of the Korean Peninsula plays a critical role in triggering elevated convection. In addition, the high-resolution LES simulation exhibits stronger spatiotemporal variability in buoyancy, convergence, and updrafts, along with clearer organization of precipitation cores, suggesting that high-resolution modeling more effectively represents the rapid evolution and pronounced variability of nocturnal LLJ-induced elevated convection.
How to cite: Kwon, S. and Shin, .: WRF simulations of an elevated convection case caused by low-level jets over the Korean Peninsula in summer, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17255, https://doi.org/10.5194/egusphere-egu26-17255, 2026.
The documentation and understanding of storms reaching severe thresholds remain limited in the Amazon. Investigating intense wind gusts and their environments is therefore essential to better understand the drivers and impacts of severe convection that can reshape forest structure, increase tree mortality, and pose risks to ecosystems and communities. This study presents the first multi-decadal (2000-2024) assessment of intense convective wind gusts (≥15 m/s) across the entire Brazilian Amazon, using hourly observations from surface weather stations from the Brazilian National Meteorological Institute (INMET). Intense wind gusts are widespread across the region and are more frequent during the dry-to-wet transition months of September and October, with a peak in the mid- to late afternoon. Wind gusts were accompanied by temperature drops, which were sharper in the dry and transition seasons (reaching −12.6°C), and pressure rises that were similar in magnitude across seasons. The atmospheric environments associated with the intense wind gusts are analyzed using the fifth-generation atmospheric reanalysis (ERA5) from the European Centre for Medium-Range Weather Forecasts (ECMWF). Wind gust environments in the Brazilian Amazon are characterized by low wind shear compared to midlatitude regions. Extreme values of deep-layer shear rarely exceed 10 m/s, with median values near 5 m/s, and show little seasonal variability, remaining weak and similar across all seasons. The results indicate that thermodynamic factors prevail in conditioning the environments that are more favorable for intense gusts observed during the dry and transition seasons, being characterized by higher downdraft convective available potential energy, steeper lapse rates, and higher lifting condensation levels, particularly in the southern Amazon.
How to cite: Ferreira, V., Santos, L. O. D., Oliveira, M. I. D., Nascimento, E. D. L., and Rammig, A.: A climatology of intense wind gusts and their atmospheric environments in the Brazilian Amazon, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17462, https://doi.org/10.5194/egusphere-egu26-17462, 2026.
Posters virtual: Mon, 4 May, 14:00–18:00 | vPoster spot 5
EGU26-1839 | ECS | Posters virtual | VPS2
Observed Lifecycle of Convective Precipitation over Tibetan Plateau Based on the FY-4A Geostationary SatelliteMon, 04 May, 14:18–14:21 (CEST) vPoster spot 5
With the intensification of global warming, deep convective system(DCS) precipitation over the Tibetan Plateau(TP) has become increasingly frequent, which plays a vital role in regulating the regional hydrological cycle. Previous studies have focused on instantaneous convective activity, little elaborating on the evolutionary processes and rainfall of DCSs throughout their whole lifecycle. Here, based on the continuous observations from the FY-4A geostationary satellite, this study investigates the characteristics and evolution of DCSs over TP from 2022 to 2023 through our previous full-lifecycle tracking algorithm from initiation to dissipation. Furthermore, the effects of key meteorological factors on DCSs evolution are revealed.
Results indicate that DCSs are mostly short-lived (3–6 h lifecycle), and more than 85% of convective precipitation occurs during summer from June to August. DCSs concentrate in the central-eastern TP, with an occurrence probability exceeding 12% in summer. Additionally, the area and rainfall rate of DCSs typically reach their peaks at the middle stage of the lifecycle. After the dissipation of the convective core, the persistence time of cirrus can reach 5%–28% of the core’s lifecycle. Controlled variable analysis reveals that convective available potential energy (CAPE) and precipitable water (PW) synergistically regulate the development of convective systems: under conditions of high CAPE (500-103 J kg-1) and high PW (>50 mm), the area of cores expands to the largest extend. However, the maximum lifecycle and peak precipitation of DCSs occur under conditions of moderate wind shear (5-10 m s-1).
This study explores the full-lifecycle evolutionary patterns of DCS over the TP and the regulatory effects of meteorological conditions over TP, laying a theoretical foundation for future research on regional precipitation and climate change in the region.
How to cite: Guo, C., Yin, J., Pan, Z., Zang, L., and Mao, F.: Observed Lifecycle of Convective Precipitation over Tibetan Plateau Based on the FY-4A Geostationary Satellite, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1839, https://doi.org/10.5194/egusphere-egu26-1839, 2026.
