Severe hail impacts and preparedness

Recent climatological study of severe hail in Finland (Tuovinen et al. 2009) shows that even on high latitudes hail can be a problem and cause injuries and locally considerable property damage. The database includes numerous events where up to 6 or 7 cm hailstones have been reported. Typically 10 severe-hail cases occur in Finland during 5 days between mid-June and mid-August, but the year-to-year variation is considerable. For example, in 2008 altogether 49 severe-hail cases occurred during 19 days.

Regardless to size, hail can flatten crops or make roads hazardous to drive with slippery conditions and rapidly decreasing visibility. As the hail size gets larger, the property damage tends to get greater. Usually plastic or glass shields or windows are deteriorated and cars dented. Typical injuries have been bruises, wounds or mild concussions. Based on past cases, we have classified typical reported hail damage in Finland for each severe hail size.

The hail damage and its' socioeconomic impacts are studied in detail for the 10 July 2006 severe hail episode, in which numerous storms with 7-cm hail swept through small cities and communities in the eastern Finland causing multimillion property damages. As an example of the damage over 1000 cars were damaged, and building windows and tile roofs were shattered.

The preparedness to prevent casualties and to minimize property damage may indeed mitigate severe hail socioeconomic impacts. Based on the observed impacts, we have developed severe hail guidance for general public: What basic steps should one take before, during and after the severe- hail event? We have also developed short “call to action statements” that can be included in severe hail warning messages.