Convective systems and periods with large precipitation in Hungary

This paper presents a study describing the synoptic scale meteorological conditions and the mesoscale structures of phenomena which can cause large amounts of convective precipitation and often flash floods in Hungary. This examination is based on radar observations, 24-hour rain gauge precipitation measurements, model analyses and forecasts in the six-year period of 2003-2010. For the investigated precipitation period, an objective procedure was applied to decide whether convection had determining role in producing of precipitation. The procedure used radar based precipitation measurements and ECMWF precipitation forecasts. ECMWF analyses and forecasts were also applied to determine the representative synoptic scale weather patterns. Based on observed radar image structures and movements of radar echoes, the mesoscale structures were identified. Studies show that most of the cases can be classified into three main clusters: events with (1) convective chains (squall lines) in the warm sector of a cyclone; (2) convective lines with related cold front; and (3) convective lines in occluded cyclones. These most common types are demonstrated by case studies. This study may help to recognize weather conditions and patterns that are responsible for flash flood events in the Carpathian Basin.