Hailstorm in the region of Central Macedonia, Greece: a kinematic study

Abstract

The purpose of this study is the analysis of radar data, digitally recorded, during an operational hail suppression program in the region of Central Macedonia, Greece, for the warm period of the years 1997-2001. Data have been quality controlled, so that only those storms unaffected by external factors be examined. Kinematic characteristics, such as lifetime and distance traveled by hailstorms, as well as direction of motion and speed, have been related to the type of storms, the synoptic environment and the season. It has been found that singlecells are short-lived and travel short distances, while multicells are long-lived and travel long distances. On the contrary, their corresponding speed distributions are similar. The deviation of the direction of motion from mean wind is smaller for singlecells than for multicells. Two classes of synoptic circulation types can be identified: one which favours long-lived storms traveling long distances and another which favours short-lived storms traveling short distances. September and July exhibit the maximum and minimum average storm speeds as a direct implication of synoptic disturbances passage and convection, prevailing respectively. Finally, storms overcoming orographic barriers decelerate in general on the windward side and accelerate on the lee side of mountains.