Abstract. Synoptic conditions prevailed during hail days in northern Greece are examined for a large sample of hail days, in an attempt to quantitatively assess weather patterns associated with the presence of hail. Within the context of the Greek National Hail Suppression Program, the initial objective of this scheme was to serve as a predictive tool for hail forecasting and permit a specification of greater or lesser hail risk. Meteorological synoptic charts were studied for all the hail days noted within the period of 1976-99 and for the warm season (April to September) of each year. Totally, seven synoptic categories were chosen with reference to 500 hPa flow and associated surface characteristics and their frequency and monthly distribution was examined. Southwest flow and shortwave trough appear to be the most conducive synoptic types for hailstorm activity. Most hailpads recorded hail during the observed hail days classified as the two above categories. Under these types was also classified the majority of the most destructive hailstorms in northern Greece.

Full-text: PDF