HAIL EPISODES AT METEOROLOGICAL STATION CRAIOVA DURING THE WARM SEASON


BĂCESCU ADRIANA, COLAN MIETTA, IORDACHESCU MAGDALENA, MĂNESCU CARMEN, VELEA LILIANA

DOI: 10.17378/AWC2015_48


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

 

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