European climatology of severe convective storm environmental parameters: A test for significant tornado events

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.