ABSTRACT | The critical factors in the determination of thunderstorm type and potential storm severity are thermodynamic and kinematic conditions. While atmospheric instability determines the strength of thunderstorm precipitation, the wind shear tends to promote storm's movement, organization and longevity. The primary goal of this study is to investigate the temporal (diurnal, seasonal, multiannual) and spatial variability of the vertical wind shears over the Mediterranean region (26.0°N – 47.0°N, 11.0°W – 42.0°E). It is based on the data derived from ERA-Interim reanalysis for the period of 1981-2015. The data consist of U and V wind components with 12-hourly sampling (00 and 12 UTC) and horizontal resolution of 0.75×0.75°. In order to compute the values of the 0-1 km, 0-3 km and 0-6 km wind shears, the information from the three hybrid-sigma levels of L60 model were used. High values of low level shear (0-1 km), defined as the difference between the wind at the lowest level and at 1 km AGL, conducive to formation of tornadoes from supercell thunderstorms as well as bowing segments producing damaging straight-line winds. The 0-3 km and 0-6 km wind shears, in turn, provide information about possibility of sustain redevelopment of new cells at outflow boundaries next to older cells, and support multicell, supercell storms and mesoscale convective systems. The preliminary results confirmed high seasonal variability of the vertical wind shears, as well as spatial heterogeneity which is related among others to the influence of the local relief. |