In late October 2024, southeastern Spain experienced severe weather, including intense rainfall, hail, and thunderstorms. On October 29th, several AEMET (Spanish Meteorological Agency) stations in the province of Valencia recorded over 300 mm of rainfall in 24 hours. This extreme event triggered flash floods and river overflows, resulting in over 200 fatalities and extensive damage to public and private property. The event was associated with a deep and persistent cut-off low (COL)—known in Spanish as DANA (Isolated Depression at High Levels)—which developed between Spain and Morocco due to the amplification of a mid-tropospheric trough. The quasi-stationary nature of this system promoted high convective instability, leading to intense, localized storms anchored over the Valencia region.

As with other extreme rainfall events worldwide, atmospheric water vapor's horizontal transport and content played a key role in creating the unstable conditions. In this case, satellite and reanalysis data estimate approximately 30 mm of precipitable water over Valencia—equivalent to a 3–4 standard deviation anomaly above climatological values. This anomalously high moisture had two primary sources: low-level easterly flow from the Mediterranean in the days leading up to the event, and an atmospheric-river-like moisture transport from the tropics across North Africa, channeled by the COL’s circulation.

In warmer conditions—whether due to transient sea surface temperature anomalies or long-term anthropogenic trends—atmospheric moisture content increases, raising the likelihood of extreme, short-duration precipitation. This study investigates the influence of anthropogenic warming on the synoptic conditions surrounding the October 2024 event. To this purpose, we analyze high-resolution (∼9 km) physical climate storyline simulations developed under the European Union’s Destination Earth initiative. These simulations were run with the global, coupled IFS-FESOM model nudged with ERA5, and include three climate scenarios: a counterfactual climate (~1950), the actual climate (~2020), and a future climate (~2040).

Results show that anthropogenic warming intensified both the instability and moisture transport associated with the COL. Specifically, about 20% of the Mediterranean moisture influx can be attributed to human-induced warming, and moisture transport from North Africa increased by ~25% in the actual climate compared to the counterfactual scenario. Overall, the Valencia region experienced 15–20% wetter conditions due to this enhanced moisture environment, resulting in approximately 12% more precipitation over Valencia and up to 20% in the surrounding areas during the event. Ongoing analyses aim to confirm these findings and explore the synoptic conditions for the event under future warming scenarios, contributing valuable insights for climate adaptation.

How to cite: Campos, D., Grayson, K., Saurral, R., Olmo, M., and Doblas-Reyes, F.: Attribution of the synoptic-scale meteorological conditions associated with the October 2024 DANA event over Valencia, Spain, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-366, https://doi.org/10.5194/ems2025-366, 2025.

The North Atlantic large-scale circulation is known to affect Mediterranean cyclonic activity, representing a unique case of interacting storm tracks. Variability in the North Atlantic, such as extratropical storm activity, jet stream position and weather regimes, modulates the flux of potential vorticity downstream. This plays a crucial role in the life cycle of Mediterranean cyclones by influencing baroclinic growth and triggering instability over the basin.

In this work, we use the framework of Finite Amplitude Local Wave Activity (FALWA; Huang & Nakamura, 2016) to deconstruct and quantify the role of the North Atlantic circulation in driving Mediterranean cyclonic activity. FALWA is a diagnostic that keeps track of the wave activity ”stored” within circulation undulations, relative to a zonalized flow. It obeys an exact conservation relation; thus, its local rate of change is either due to a flux convergence, or to non conservative source-sink terms. This allows for a closed mechanistic budget analysis of the response, differentiating between horizontal advection by the mean flow, barotropic and baroclinic processes, and diabatic forcing. To the best of our knowledge, the method has not yet been applied to the Mediterranean.

Using reanalysis, we examine how extrabasin sources of wave activity influence the paths, intensity and associated rainfall patterns of storms in the Mediterranean. We find that different combinations of advective and baroclinic sources result in distinct cyclone trajectories, impacting precipitation at both 10-day and monthly scales. We are currently producing preliminary results from the CMIP6 ensmeble and exploring the relevance of this mechanism to the projected drying trend in the Mediterranean.

How to cite: Sandler, D., Saaroni, H., Ziv, B., and Harnik, N.: A New Quantitative Framework for Mediterranean Cyclogenesis: Local Wave Activity and Cross-Basin Dynamics, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-454, https://doi.org/10.5194/ems2025-454, 2025.

We present a physical storylines study of storm Gloria, a devastating extra-tropical cyclone in January 2020 over the western Mediterranean that caused record-breaking precipitation, fatalities, and millions in damages. The study is performed using the global, coupled, km-scale IFS-FESOM model, developed under the European Union’s Destination Earth initiative. We run the model using spectral nudging, where the upper atmosphere is nudged hourly with ERA5 reanalysis to recreate the observed weather patterns in a Counterfactual (cooler, ~1950’s), Actual (~2020) and Future (warmer, ~2040’s) background climate. The ~9 km, hourly resolution allows us to analyze localized extreme precipitation at scales useful for adaptation planning. 

The work will be presented in two parts. In the first section we will present a novel probabilistic attribution study using the climatology of the storyline simulations, quantifying the changes in probability of key atmospheric variables observed during Gloria in a warmer climate. This is made possible due to the continuous 7-year runs of the global storyline simulations, allowing us to build DJF climatologies for the three different climate scenarios. We find that all atmospheric variables show statistically significant increases, with Gloria-level precipitable water over twice as likely to occur in the Future climate scenario. 

In the second part we present an in-depth comparison of the event under different climates, both in terms of atmospheric drivers and hydrologic impacts analyzed via a runoff model. We find that while precipitable water and integrated vapor transport follow Clausius-Clapeyron scaling, extreme precipitation shifts locally, increasing up to 45% in some areas but not always translating to higher runoff due to drier soils. Though focused on storm Gloria, we emphasize the global nature of these simulations and their contribution to equitable access to climate adaptation information in the analysis of extreme events. Indeed, we refer to the abstract by Campos D, “Attribution of the synoptic-scale meteorological conditions associated with the October 2024 DANA event over Valencia, Spain” who uses the same simulations to understand the impacts of warming of the recent DANA event over Valencia.

How to cite: Grayson, K., Campos, D., Versteeg, G., Kelbling, M., Chandrasekar, A., Thober, S., Beyer, S., and Doblas-Reyes, F.: The influence of anthropogenic warming on Storm Gloria: a km-scale storyline approach, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-502, https://doi.org/10.5194/ems2025-502, 2025.

Simulating the response of local climate to the Earth global warming is a challenge. In coastal areas, it is mandatory to integrate the response of the sea to the progressive increase of the atmospheric temperature, the changes in the inland precipitation regimes and the surface wind field pattern. In this frame, the Mediterranean area is a benchmark, where atmosphere and sea interact with a high degree of coupling, besides to be a hot spot rising deep interest for its evolution.

Future climate scenarios for both atmosphere and sea over Mediterranean are already available form a rich set of regional climate simulation. Anyway, stakeholders require information on future climate having a spatial resolution higher than that characterizing the regional scale. Furthermore, many local process of interaction between atmosphere, hydrosphere and sea, especially along the coasts and in shallow waters, have a poor representation in the available model outputs. Downscaling is applied to regional climate and basin scale simulations with the aim to fill in the gap.

In this work, we present the application of a methodology to generate ensembles of high resolution simulations at the local scale, for the widely and commonly defined Global Warming Levels (GWLs: 1.5 °C, 2.0 °C, 3.0 °C, 4.0 °C). Using boundary conditions extracted from sets of EURO-CORDEX, MED-CORDEX and CMIP6 model outputs, ensembles of hydrological projections combined with hydrodynamic simulation of the Adriatic Sea shallow waters have been conducted to explore the air-rivers-lagoon-sea response to the GWLs across the XXI century. Hydrological simulations have been generated by means of the WRF-Hydro model, while the lagoon-sea ones through the SHYFEM numerical model.

From sensitive tests on the response of small spatial domains to the forcing and boundary conditions, we conclude that the effort to run very high resolution models covering continuously secular time range, is not an efficient approach. Instead, the quick response of the hydro-coastal system to the boundary and the forcing allows to generate a large set of local area sensitivity cases to the GWLs, with computational resources and times that are worth to be considered useful besides efficient.

This approach explores decadal time window ensembles of future scenarios, each belonging to the same GWL, with the spatial resolution requested by a wide spectrum of stakeholders on future river flows, temperature, salinity and level along the coasts, in the lagoons and in the open sea facing the coastal areas. In addition to the summary of the methodology, we present the results of its application to the northern Adriatic Sea, including the northeastern most lagoon.

This work has been conducted with the contribution from the EU co-financing in the frame of the Interreg Euro-MED Programme, thanks to the MedSeaRise Project, and the results achieved through the Interreg IT-HR AdriaClimPlus project.

How to cite: Minigher, A., Cioffi, C., Moro, C., Giaiotti, D., Gianesini, E., Zampar, M., and Bacer, S.: Towards very high resolution downscaling of climate scenarios for Mediterranean coastal areas, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-675, https://doi.org/10.5194/ems2025-675, 2025.

The 2022 drought was part of a multi-year drought that began in 2021 and continued until the middle of 2023. Multi-year droughts pose a significant threat to the security of water resources, putting stress on the resilience of hydrological, ecological and socioeconomic systems. Motivated by the recent multi-year drought that affected Southwestern Europe and Italy from 2021 to 2023, here we utilise two indices—the Standardised Precipitation Evapotranspiration Index (SPEI) and the Standardised Precipitation Index (SPI)—to quantify the temporal evolution of the percentage of Italian territory experiencing drought conditions in the period 1901–2023 and to identify Widespread Multi-Year Drought (WMYD) events, defined as multi-year droughts affecting at least 30% of Italy. Seven WMYD events are identified using two different precipitation datasets: 1921–1922, 1942–1944, 1945–1946, 2006–2008, 2011–2013, 2017–2018 and 2021–2023. Correlation analysis between the time series of Italian drought areas and atmospheric circulation indicates that the onset and spread of droughts in Italy are related to specific phases of the winter North Atlantic Oscillation (NAO), the Scandinavian Pattern (SCAND), East Atlantic/Western Russia (EAWR) pattern and the summer East Atlantic (EA) and East Atlantic/Western Russia (EAWR) patterns. Event-based analysis of these drought episodes reveals a variety of atmospheric patterns and combinations of the four teleconnection modes that contribute to persistently dry conditions in Italy during both winter and summer. This study offers new insights into the identification and understanding of the meteorological drivers of Italian WMYD events and serves as a first step toward a better understanding of the impacts of anthropogenic climate change on them.

How to cite: Pascale, S. and Ragone, F.: Widespread Multi-Year Droughts in Italy: Identification and Causes of Development, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-260, https://doi.org/10.5194/ems2025-260, 2025.