HAIL SUPPRESSION PROGRAM IN LEÓN (PALA) FROM 1986 TO 1999: SPATIAL DISTRIBUTION OF THE HAIL PRECIPITATION IN SEEDING PERIODS AND PERIODS WITH NO SEEDING ACTIVITIES

In 1986 began a Hail Suppression Program in León (Spain), which was aimed at analyzing the problems caused by hail and finding solutions. In order to achieve this purpose several observation networks were set up in a previously delimited study zone of almost 7,000 km2. A network of remote ground generators was installed in 1993. This network was set up with hail suppression purposes and it should protect part of the study zone, an area of approximately 3,500 km2.

The facts mentioned above have allowed the comparison of hail precipitation in periods with and without seeding activities, in the whole of the study zone 7,000 km2, and in the subarea of 3,500 km2. Moreover, the meteorological situations in the two different types of periods have also been characterized and compared.

The results are very interesting, since they show that: In wide areas within the seeded zone the hailfalls decreased. There are no significant differences between one period and the other in the area that was not seeded. The meteorological conditions during the seeding period presented higher risks of thunderstorms than the situations in the period with no seeding activities.