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Abstract: A climatology of various parameters associated with severe convective storms has been constructed for Europe. This involves using the reanalysis data base from ERA-40 for the period 1971–2000 and calculating monthly means, variability range and extremes occurrence of fields such as convective available potential energy, convective inhibition energy, mid-tropospheric lapse rate, low-tropospheric moisture content and storm relative helicity for different layers. This process is a first step towards development of a synthetic climatology of European severe weather, and is publicly available at the web site http://ecss.uib.es. Preliminary results derived from these products were presented during the ECSS 2004 conference. This paper is devoted to a more detailed presentation and discussion of the main results. It is hypothesized that preferred areas for severe thunderstorms occurrence in Europe would extend along a zonal belt over the south-central regions, where high helicity associated with the extratropical storm tracks and thermodynamically-favourable profiles established over the southern Atlantic and Mediterranean Sea would most likely be concatenated. Further, this effort has been complemented with a collection of existing reports of significant (at least F2) tornadoes in Europe during the period 1971–2003. We present this data set in this paper and it also can be found at the website http://ecss.uib.es. Thus, the tornado collection can be used to test the appropriateness of the parameters selected for the synthetic climatology. In particular, it is found that the convective available potential energy, low-tropospheric moisture content and environmental shear, when related to the monthly climatology, are reasonably good descriptors of the tornadic environments. [Copyright &y& Elsevier]

Abstract: This paper is devoted to a case study of one of the best-known historical severe storms in Europe. Organised convective systems with the characteristic behaviour of a supercell storm evolved in a meso-α scale convective complex, and the locally damaging weather affected a strip of land from Switzerland to Poland. The development of the storm resulted from a specific combination of processes at various spatial and temporal scales. This study focuses on an analysis of the synoptic and sub-synoptic meteorological conditions before and during the event. The re-analyses ERA-40 are used to investigate anomalies of dynamic and thermodynamic quantities at the synoptic scale. It is demonstrated that some quantities may reach abnormal values not only during large-scale precipitation events, but also during a case of severe convection. The non-hydrostatic limited-area NWP model COSMO is employed to re-forecast the event and to investigate the specific features of the convection environment with a horizontal resolution of 2.8 km. The skill of the re-forecast of precipitation is evaluated using verification methods based on selected categorical skill scores and area-related root mean square error values. Simulated precipitation and radar data show good agreement with observations in terms of daily totals and the spatio-temporal evolution of the storm. The outputs from the diagnostic Model for the Objective Analysis of Gust Fronts indicate that the simulated convection environment does not differ significantly from the real conditions. In addition, the analysis reveals vertical shear and stability conditions favourable for the intensification of convective processes by propagating gust fronts in the areas where new convection formed. [Copyright &y& Elsevier]