The Black Sea influence in convective storms initiation in South Eastern Romania

The Romanian severe convective storms, as revealed by the NEXRAD-like network, do not cease to enchant and challenge the forecasters by the diversity of forms and processes involved. The initiation of severe storms is the focus of this paper. We investigate mainly the role of the Black Sea as a source of moisture, wind convergence and shear in initiating convective storms in the South Eastern part of Romania; the sea breeze front and its intersection with gust fronts, horizontal convective rolls, convergence zones and lines is presented, together with the associated conceptual models for storms initiation. Among the forecasters there was the belief that the sea breeze front and its influence can not penetrate inland more than 30 km, but we present cases where this influence can reach over 100 km. We present our actual knowledge of the Black Sea breeze effects on convection, for different types of general circulation. We also present some of the most severe cases that produced tornadoes, flash floods, intense lightning activity, strong winds and large hail. The figure bellow is a mosaic of 4 images: in the upper line there are two cases of tornadic storms that initiated near the sea breeze front and a convergence zone; fortunately there was no victim and the tornadoes have been recorded on video. In the bottom line is an initiation case where the sea breeze had an interaction with horizontal convective rolls and other boundaries present. The first image is a satellite visible high resolution image, and the rest are radar reflectivity images. The similarity with the NEXRAD conceptual models and appearance of storms is not intended but obvious, and inspires us to consider that convection is the same all over the world, but what differs is our ability to apply what is already known. In order to encourage cooperation among neighboring countries to study severe convection on a regional approach, three of these cases have been recently used in international training workshops hosted by the National Meteorological Administration of Romania; forecasters from many countries in South Eastern Europe worked together to develop mesoscale conceptual models for storms initiation in the basin of the Black Sea. The radar data, provided by the WSR-98D network, have been complemented with lightning, satellite, sounding and NWP data from hydrostatic and non-hydrostatic models (ALADIN, ALARO, COSMO) used in operational environment.