Comparison of Hail Characteristics in NW Croatia for Two Periods

Abstract

This paper presents hail characteristics for two separate periods (1981–1990,1991–1999) in the western part of the hail protected area along the Croatianand Slovenian border. The first period is characterised by full application ofhail suppression technology. The protected area was covered with a sufficientnumber of hail suppression rockets, rockets launching was permitted across theSlovenian border aimed at early seeding, and Slovenia in that time had also theoperative hail suppression system. The second period is characterised withsignificantly lower application of hail suppression technology compared withfirst period. During the independence war in Croatia, because of a lack ofrockets and other objective circumstances, appropriate rocket hail suppressionwas missing. This work examines whether hail characteristics on the border areahave changed, taking into account the changes in suppression. Results show thatthe average diameter of hailstones and duration of hailfall slightly increasedin second period. Also, there is an increase in the number of areas with alarger ratio of hail producing heavy damage, compared with first period. On thebasis of data from five meteorological stations, it is visible that, as a resultof implementation of the hail suppression system, the average number of dayswith solid precipitation on that area in period April–October has reduced,compared with the period when there was no hail suppression system.