HAIL EPISODES AT METEOROLOGICAL STATION CRAIOVA DURING THE WARM SEASON
BĂCESCU ADRIANA, COLAN MIETTA, IORDACHESCU MAGDALENA, MĂNESCU CARMEN, VELEA LILIANA
ABSTRACT. Hail episodes at meteorological station Craiova during the warm season. The paper presents a statistical, climatological study of the occurrence of hail phenomenon at Craiova- one of the representative stations in Oltenia region – during months May-August in the period 1981-2010. The results show that the month with most hail cases during the period analyzed is June, while the largest frequency of occurrence corresponds to time interval 13:30-14:30 UTC; regarding the dimensions of hail, in most cases the hail particles presented diameters up to 5 mm. From a synoptic point of view, the frequency of thermal convection as trigging factor for hail episodes at Craiova was larger (54%) compared to that of dynamic convection. There are also presented the synoptic and mesoscale conditions which generated this phenomenon in two distinct cases: one generated by thermal convection, observed in 8 June 2013, and the other by dynamic convection, occurred in 14 April 2012. The synoptic and mesoscale conditions during the day of 8 June 2013 favored the occurrence of hail Craiova station due to the weak synoptic forcing and to a relatively warm and wet boundary layer, thus meeting two of the conditions of mass instability. In the second case, the baric configuration at sea level, presenting a low in the west-central basin of Mediterranean, was supported in the middle troposphere, at the 500hPa level, by the presence of a trough extending over most of the Europe, up to the south. The hail was generated, in this case, by the occluded front associated with the Mediterranean depression.
Keywords: hail occurrence, synoptic conditions, thermal and dynamic convection