THE EPISODIC OCCURRENCE OF HAIL IN CENTRAL ALBERTA AND THE HIGHVELD OF SOUTH-AFRICA

The frequency and duration of hail day episodes were analyzed based on 29 summers of hail data from central Alberta, Canada and 19 summers o f data from the Highveld South Africa. A hail episode consists of one or more consecutive days with at least one hail report. A severe hail episode is defined as an episode that has at least one day of maximum hail size greater than or equal to 33 mm for Alberta, (greater than or equal to 31 mm for the Highveld). Severe and non-severe hail episodes are found to occur, on average, 6.6 and 11.2 times in Alberta, respec tively, with mean durations of 4.2 and 2.1 days. In the Highveld sever e and nonsevere hail episodes occur, on average, 2.8 and 21.9 times pe r six-month summer and have mean durations of 4.9 and 2.5 days.