European Heat Waves Send Energy Waves That Fueled China’s Record April 2024 Floods

In April 2024, the southern Chinese province of Guangdong was drenched by the heaviest April rainfall it had seen since records began in 1951. Rivers burst their banks, cities flooded, and forecasters struggled to explain why the pre-flood season had turned so destructive. A new study published in Climate Dynamics now traces an unexpected culprit thousands of kilometers away: a persistent and extreme heat anomaly over Eastern Europe, whose energy was carried across the Eurasian continent by atmospheric waves and converted into the fuel that powered the deluge.

The research, led by Yina Diao and Jianping Li of the Ocean University of China together with colleagues, approaches the problem through an energy lens. Rather than asking only which winds and pressure patterns aligned over South China, the team examined perturbation potential energy, or PPE, a diagnostic quantity that measures the energy stored in deviations of the atmosphere from its background state. First developed as an extension of Edward Lorenz’s classic concept of available potential energy, PPE tracks how much energy is locked into temperature and pressure anomalies and is available to be converted into the kinetic energy of motion, including the vigorous updrafts that drive heavy rain.

The analysis revealed that the record warmth over Eastern Europe in April 2024 was accompanied by an unusually large reservoir of Eastern Europe PPE, abbreviated EEPPE in the study. That energetic anomaly did not sit still. It acted as a stable wave source, amplifying and sustaining a Rossby wave train that the authors call the Eastern Europe high–West Asia low, or EEWA, pattern. This wave train is a chain of alternating high and low pressure anomalies that stretches from Eastern Europe across West Asia toward East Asia, and it serves as the dynamical bridge connecting the two seemingly unrelated extremes: scorching heat in Europe and flooding in southern China.

According to the study, the EEWA wave train reshaped the thermodynamic environment over Guangdong through two distinct pathways. The first acts high in the atmosphere: the wave train modulated the upper-tropospheric westerly jet that flows south of the West Asian low, and changes in the jet altered the vertical motion over South China. Stronger rising motion is a prerequisite for heavy precipitation, because air that ascends cools, water vapor condenses, and latent heat is released. The second pathway operates closer to the surface: the wave pattern modified local thermal advection over Guangdong, pumping warm air into the region and thereby increasing the local PPE, the stored energy available for conversion into storm-scale motion.

The two pathways converged in a mutually reinforcing sequence. As EEPPE increased, vertical velocity over Guangdong strengthened and the local PPE pool deepened. The enhanced upward motion then facilitated the conversion of that local perturbation potential energy into kinetic energy, intensifying the very convection that produced the torrential rain. In energy terms, the atmosphere over southern China was primed with potential energy by remote heating anomalies, and the large-scale dynamics supplied the trigger that unlocked it. This chain of events establishes, for the first time in such a quantitative framework, a direct dynamical link between heat extremes in Eastern Europe and flooding in Guangdong.

One of the most consequential findings of the study is its implications for early warning. The PPE anomalies over Eastern Europe build up roughly a week before the extreme precipitation peaks over Guangdong, meaning that EEPPE can serve as a one-week precursor signal. In operational terms, an energy diagnostic computed over Eastern Europe could give forecasters in South China valuable lead time, complementing conventional monitoring of tropical influences such as the Madden–Julian Oscillation and sea-surface temperature patterns in the Indo-Pacific, which other studies have also implicated in the April 2024 event.

The researchers were careful to test whether this hot-flood teleconnection was a one-off curiosity of 2024. Their analysis shows that it was not. The connection between Eastern European heat-related PPE and Guangdong rainfall has persisted since the early twenty-first century, suggesting a robust and recurring dynamical pathway. What made April 2024 exceptional, the study concludes, was the prolonged and extreme nature of the European heat anomaly, which sustained the EEWA wave train long enough to drive long-lasting extreme precipitation in Guangdong rather than a brief burst of heavy rain.

The findings arrive at a moment when scientists are increasingly recognizing that climate extremes do not respect continental boundaries. Heat waves and floods are often treated as separate hazards in separate regions, but the atmosphere transports their consequences around the planet through teleconnections. Just as sea-surface temperature anomalies in the tropical Pacific can reshape winters in North America, extreme heating over Eastern Europe can, through wave dynamics and energy conversion, help set the stage for catastrophic rainfall in East Asia. As heat extremes intensify under global warming, the study suggests that the frequency and severity of such remote hot-flood linkages may change as well.

Technically, the work showcases the growing utility of PPE as a diagnostic tool in climate research. Unlike purely statistical correlations between distant weather events, the PPE framework traces the actual energetic pathway: heat anomalies build potential energy in one region, wave trains transport its influence downstream, and energy conversion processes release it as the kinetic energy of storms. Earlier applications of the framework have illuminated the energetics of the South China Sea summer monsoon, the Indian Ocean Dipole, and multidecadal variability in the North Atlantic, and this study extends the method to the attribution of a specific record-breaking disaster.

For Guangdong, home to more than 120 million people and the Pearl River Delta megacity cluster, the practical message is sobering. The province’s pre-flood season, already among the rainiest in East Asia, can be supercharged by heat events unfolding a continent away, and the energy fingerprints of those heat events are visible in advance. If the hot-flood teleconnection holds as warming continues, monitoring atmospheric energy reservoirs over Eastern Europe may become as important for South Chinese flood preparedness as watching the skies overhead. The study, supported by China’s National Key Basic Research Project, the National Natural Science Foundation of China, and Laoshan Laboratory, relied on the European Centre for Medium-Range Weather Forecasts ERA5 reanalysis and rainfall observations from the China Meteorological Administration, providing a data-rich foundation for what may become a new chapter in extreme-event forecasting.

The physics underlying the teleconnection rests on a well-established principle of midlatitude dynamics: stationary Rossby waves. When a large-scale heat source perturbs the atmosphere, it displaces air parcels and generates wave energy that propagates along the westerly jet stream. The theoretical foundations for describing this propagation were laid decades ago, from the classic energy-transfer analysis of Eliassen and Palm to later work by Karoly and Plumb on wave activity in sheared and three-dimensional flows. The EEWA wave train identified in the Guangdong study is a contemporary application of this lineage, demonstrating how a thermal anomaly over Eastern Europe can impose a coherent chain of circulation anomalies across the Eurasian continent within days.

The choice of perturbation potential energy as the central diagnostic is itself notable. Traditional analyses of heavy rainfall in South China have emphasized circulation patterns, moisture transport, and convective instability, often drawing on case studies of the pre-flood season that stretches from April through June. The PPE framework reframes these questions energetically: instead of describing where winds converge, it quantifies how much exploitable energy the atmosphere holds and where that energy is created, stored, and destroyed. Because PPE responds directly to diabatic heating, it is particularly sensitive to the kind of prolonged surface warming that characterized Eastern Europe in spring 2024, making it a natural bridge between heat extremes and downstream storm development.

The data underpinning the analysis also merit attention. The ERA5 reanalysis, produced by the European Centre for Medium-Range Weather Forecasts, assimilates observations into a globally consistent record extending back to 1940, allowing anomalies in April 2024 to be placed in a seven-decade context. Pairing this with station-based rainfall observations from the China Meteorological Administration enabled the researchers to verify that the record April precipitation in Guangdong coincided precisely with the phases of the wave train and the energy conversions diagnosed from reanalysis fields, rather than resting on model simulations alone.

The finding that the hot-flood linkage has persisted since the early twenty-first century raises questions about what may have established it. Prior research has documented interdecadal shifts in the factors governing spring rainfall over southern China, including changes in the influence of Eurasian snow cover and in the behavior of the first rainy season itself. Whether the emergence of the EEPPE–Guangdong connection reflects a genuine reorganization of waveguide dynamics, a consequence of warming-driven increases in heat extremes over Europe, or simply the window of the observational record remains an open question that future work will need to address.

For forecasters, the one-week lead time implied by EEPPE anomalies sits in a valuable gap between short-range weather prediction and seasonal outlooks. Subseasonal forecasting has long struggled with the so-called predictability desert, the span beyond about ten days where deterministic forecasts lose skill but seasonal signals have not yet emerged. An energy-based precursor rooted in a physically understood wave mechanism offers a complementary handle on this range, and the study’s demonstration that the signal is recurrent rather than unique to 2024 strengthens the case for testing it in an operational setting.

More broadly, the work adds to a growing catalog of remote linkages in which extremes in one region amplify hazards in another. As the atmosphere warms, the amplitude of heat-driven energy anomalies is expected to grow, potentially strengthening the wave sources that seed such teleconnections and making energy diagnostics an increasingly important part of hazard monitoring worldwide.

Subject of Research: The dynamical teleconnection linking Eastern European heat extremes to extreme precipitation in Guangdong, China through atmospheric wave trains and perturbation potential energy conversion

Article Title: A hot-flood teleconnection as a key contributor to the extreme April 2024 precipitation in Guangdong

Article References: Diao, Y., Zhang, X., Li, J., Yang, Y., Zhang, Y., Huang, F., & Hou, Z. (2026). A hot-flood teleconnection as a key contributor to the extreme April 2024 precipitation in Guangdong. Climate Dynamics, 64(10), Article 421. https://doi.org/10.1007/s00382-026-08372-0

Image Credits: AI Generated

DOI: 10.1007/s00382-026-08372-0

Keywords: extreme precipitation, perturbation potential energy, hot-flood teleconnection, Guangdong floods, Eastern Europe heat, Rossby wave train, Climate Dynamics, ERA5 reanalysis, atmospheric dynamics, extreme weather, South China rainfall, energy conversion