Damaging hailstorms in South Moravia, Czech Republic, in the seventeenth to twentieth centuries as derived from taxation records

Hailstorms are among the hydrometeorological extremes recognised in the historical past of the Czech Lands as grounds for tax relief if agricultural crops or material structures were damaged by them. The administrative process involved three levels (community, regional office, land office). The damage reports and taxation records for South Moravia (the southeastern parts of today’s Czech Republic) were mainly stored in the Moravian Land Archives at Brno in estate accounts and collections of family archives. Data related to the date of a given hailstorm, its accompanying convective phenomena, the communities affected and the type of damage, as interpreted from taxation records, has created a database spanning the years 1650 to 1941 AD. A total of 766 records contain descriptions that cover 433 days upon which hailstorms did damage in South Moravia, as well as incidentally provide some additional information for the remainder of the Czech Lands and other parts of the Austro-Hungarian empire. The hailstorms detected concentrate to a large extent around the 1821–1850 period, which accounts for 44.4 % of all events. Although reported most frequently without other convective phenomena, they were often accompanied by torrential rain. The current contribution analyses the four most outstanding hailstorms in detail, those characterised by the highest number of estates and communities affected: 26 May 1830, 18 July 1832, 25 June 1844 and 20 June 1848. Uncertainties in hailstorm data, particularly with regard to their spatial and temporal heterogeneity, are discussed. Finally, the 1811–1850 period, with the highest number of hailstorm days, is compared with hailstorm patterns that derive from systematic meteorological observations in the 1961–2000 reference period. Damaging hailstorms disclosed by taxation data will be used to compile long-term hailstorm series for South Moravia (together with those derived from other documentary evidence and systematic meteorological observations).