Many cyclone detection and tracking methods (CDTMs) have been developed in the past to study the climatology of extratropical cyclones. However, all CDTMs have different approaches in defining and tracking cyclone centers. This naturally leads to cyclone track climatologies with inconsistent physical characteristics. More than that, it is typical for CDTMs to produce a non-negligible number of tracks of weak atmospheric features, which do not correspond to large-scale or mesoscale vortices and can differ significantly between CDTMs. Lack of consensus in CDTM outputs and the inclusion of significant numbers of uncertain tracks therein have long prohibited the production of a commonly accepted reference dataset of extratropical cyclone tracks. Such a dataset could allow comparable results on the analysis of storm track climatologies and could also contribute to the evaluation and improvement of CDTMs. To cover this gap, we present a new methodological approach that combines overlapping tracks from different CDTMs and produces composite tracks that concentrate the agreement of more than one CDTM. In this study we apply this methodology to the outputs of 10 well-established CDTMs which were originally applied to ERA5 reanalysis in the 42-year period of 1979–2020. We tested the sensitivity of our results to the spatiotemporal criteria that identify overlapping cyclone tracks, and for benchmarking reasons, we produced five reference datasets of subjectively tracked cyclones. Results show that climatological numbers of composite tracks are substantially lower than the ones of individual CDTMs, while benchmarking scores remain high (i.e., counting the number of subjectively tracked cyclones captured by the composite tracks). Our results show that composite tracks tend to describe more intense and longer-lasting cyclones with more distinguished early, mature and decay stages than the cyclone tracks produced by individual CDTMs. Ranking the composite tracks according to their confidence level (defined by the number of contributing CDTMs), it is shown that the higher the confidence level, the more intense and long-lasting cyclones are produced. Given the advantage of our methodology in producing cyclone tracks with physically meaningful and distinctive life stages, we propose composite tracks as reference datasets for climatological research in the Mediterranean. The Supplement provides the composite Mediterranean tracks for all confidence levels, and in the conclusion we discuss their adequate use for scientific research and applications.

As the European continent and the Mediterranean Sea experience rapid warming trends and diverse manifestations of extreme weather, there is an urgent need to understand and mitigate the impacts of climate change in these regions. This study introduces the Computational Hydrometeorology with Advanced Performance to Enhanced Realism (CHAPTER) high‐resolution dynamical downscaling of the European Centre for Medium‐Range Weather Forecasts Reanalysis v5 (ERA5) global reanalysis made with the Weather Research and Forecasting numerical model. CHAPTER covers Europe and the Mediterranean basin at a convection‐resolving grid resolution of 3 km by 3 km. CHAPTER's performances in representing precipitation and temperature are evaluated compared to state‐of‐the‐art datasets like ERA5‐Land. The focus is put on seasonal spatial distributions of the bias and the root mean square error, and fuzzy verification techniques are used to validate the precipitation outputs. The results reveal that CHAPTER's performance aligns closely with well‐recognized downscalings of ERA5 but has, in addition, the advantage of providing a rich portfolio of variables at hourly temporal resolution and on different terrain, following model levels. Therefore, CHAPTER is a valuable resource for studying extreme weather events, offering insights crucial for climate change adaptation and mitigation efforts in Europe and the Mediterranean region.

Cyclonic perturbations in the Mediterranean region sometimes acquire characteristics typical of tropical cyclones, such as a deep inner warm core. In these cases, they become very intense structures that can cause large precipitations and significant damage. In this study, the environmental conditions during the intensification of cyclones are investigated using reanalysis data. A comparison of the conditions associated with the evolution of classical and intense cold-core extratropical cyclones and those associated with the development of tropical-like disturbances highlights the characteristic that favors the conversion: a much larger potential intensity and a weaker vertical wind shear. The larger potential intensity associated with Mediterranean tropical-like cyclones comes from both higher SST and a strong PV-intrusion that destabilizes the air column. Sea surface cooling induced by the cyclones is further shown to play a role in the dissipation of tropical-like cyclones. Future research should focus on the role of potential intensity as a precursor for Mediterranean tropical-like cyclone forecasting, improving predictive capabilities and risk mitigation strategies in the Mediterranean region.

Cyclonic perturbations in the Mediterranean region sometimes acquire characteristics typical of tropical cyclones, such as a deep inner warm core. In these cases, they become very intense structures that can cause large precipitations and significant damage. In this study, the environmental conditions during the intensification of cyclones are investigated using reanalysis data. A comparison of the conditions associated with the evolution of classical and intense cold-core extratropical cyclones and those associated with the development of tropical-like disturbances highlights the characteristic that favors the conversion: a much larger potential intensity and a weaker vertical wind shear. The larger potential intensity associated with Mediterranean tropical-like cyclones comes from both higher SST and a strong PV-intrusion that destabilizes the air column. Sea surface cooling induced by the cyclones is further shown to play a role in the dissipation of tropical-like cyclones. Future research should focus on the role of potential intensity as a precursor for Mediterranean tropical-like cyclone forecasting, improving predictive capabilities and risk mitigation strategies in the Mediterranean region.

Extreme weather events such as heavy precipitation and droughts are key indicators of climatechange, yet their variability and underlying drivers remain challenging to assess. This studyinvestigates trends in extreme precipitation over Europe and the Mediterranean from 1981 to 2022using CHAPTER (Computational Hydrometeorology with Advanced Performance to EnhancedRealism), a high-resolution (3 km × 3 km). CHAPTER is a convection-permitting dynamicaldownscaling of the ERA5 global reanalysis, performed with the WRF numerical model. The highspatial resolution of CHAPTER enables a detailed analysis of convective processes that globalclimate models cannot directly represent. A robust physical scaling diagnostic is applied todecompose changes in hourly extreme precipitation into thermodynamic and dynamic contributions.Results indicate an overall increase in extreme precipitation intensity of 2.5% per degree ofwarming, with significant regional variations. The strongest increases are observed over the easternMediterranean, particularly in the Ionian Sea, while slight decreases appear over the IberianPeninsula and the western French coasts. These spatial patterns strongly correlate withthermodynamic scaling, suggesting that precipitation changes at a regional scale are primarilydriven by increasing atmospheric moisture content, consistent with global-scale findings. Morespecifically, these spatial trends in extreme precipitation closely align with surface changes inspecific humidity.Conversely, the dynamic contribution exhibits significant spatial variability, suggesting a stronginfluence of natural variability over the 42-year period studied. A statistical significance testconfirms that most observed trends in extreme precipitation are not robust at a 95% confidencelevel, reinforcing the hypothesis that natural variability plays a dominant role.

Cyclonic perturbations in the Mediterranean region sometimes acquire characteristics typical of tropical cyclones, such as a deep inner warm core. In these cases, they become very intense structures that can cause large precipitations and significant damage. In this study, the environmental conditions during the intensification of cyclones are investigated using reanalysis data. A comparison of the conditions associated with the evolution of classical and intense cold-core extratropical cyclones and those associated with the development of tropical-like disturbances highlights the characteristic that favors the conversion: a much larger potential intensity and a weaker vertical wind shear. The larger potential intensity associated with Mediterranean tropical-like cyclones comes from both higher SST and a strong PV-intrusion that destabilizes the air column. Sea surface cooling induced by the cyclones is further shown to play a role in the dissipation of tropical-like cyclones. Future research should focus on the role of potential intensity as a precursor for Mediterranean tropical-like cyclone forecasting, improving predictive capabilities and risk mitigation strategies in the Mediterranean region.