Thilo Kühne from the ESSL team, working on ESWD data and quality control, collected rare cases of tornadoes crossing national borders.

While the maintenance of a tornadic circulation is only a matter of physical variables and not influenced by political boundaries, there is still a statistical issue when it comes to the counting of tornado cases on a national level. This article discusses examples, the historical practice and current ESWD policy for such cases.

Read the full story here (PDF).