The situation is paradoxical. Hail is a natural hazard that causes immense damage in many parts of Europe, yet there has been very little scientific exchange over this costly phenomenon. “Worldwide, there probably hasn’t been a single scientific event dealing exclusively with hail – until now,” said Olivia Romppainen, one of the organisers of the “1st European Hail Workshop” presented by the Oeschger Centre and Mobiliar Lab. This made the international participation all the more gratifying. Researchers from around Europe – including Spain, Britain, Germany, Belgium, Poland, Bulgaria and Greece – all made the trip to Bern. Representatives of the American and Canadian national weather services also took part.
Thematically, the workshop was as diverse as possible. The presentations and discussions revolved around the microphysics of hailstorms as well as the challenges for the insurance industry and so-called nowcasting – which gives hail warnings anywhere from a few minutes to a few hours in advance. “The conference provided an excellent overview of the various aspects of hail,” said Olivia Romppainen in summary. Last but not least, insurance companies offered a look behind the scenes and showed which modelling methods they use to predict the risk of hail.
Blinds cost more than windows
When it comes to prevention, the insurance companies follow a rule of thumb that their clients often find hard to embrace; when there’s hail, raise the external blinds. The reason for this is that windows are rarely damaged, and even if they are, they’re less expensive to replace than hail-dented blinds.
Another block of presentations was devoted to hail climatology. Nearly all countries collect data on the frequency and magnitude of hail storms, drawing on radar measurements and ground observations – but with the same techniques and problems. The data are always limited to a specific territory. As one participant wondered, why does hail climatology tend to stop at national borders? “A good question; we can try to improve this at the next workshop,” said Olivia Romppainen. According to the assistant professor for climate risks at the University of Bern, part of the reason is the huge amounts of data involved in keeping hail statistics.
Better hail forecasts for farmers
Both researchers and industry representatives were very interested in the presentations on “nowcasting”. Today’s usual warnings, ideally an hour or two – but often just a few minutes – before the onslaught of hail might be sufficient to move cars to safety, but are of little use to agriculture. This shows the need for significant progress in the area of prediction models. Olivia Romppainen said there were many meteorological services worldwide working on such improvements. “But there’s still a lack of explicit models for hail; the necessary microphysics schemes are just being tested now.”
Whether it’s hail warnings or other issues, there’ll be no shortage of material for the next European hail workshop. One big issue that research has hardly tackled is climate change and hail. “We only discussed this subject on the side lines because the need for research is still huge,” explained workshop organiser Olivia Romppainen.
