Abstract
A classification method is suggested and applied to distinguish the variants of synoptic-scale patterns inducing heavy, widespread, and steady rains in the Czech Republic. The method is based on divisive hierarchical fuzzy clustering of the 78 heaviest rainfall events that affected various parts of the Czech territory in the warmer half-years from 1958 to 2002.
The degree of moisture flux close to the rainfall area is selected as a similarity criterion for clustering. Four clusters of the events obtained by the second level of clustering are discussed.
Two frontal and two cyclonic variants are distinguished. The frontal variants are characterized by the recurring passage of frontal waves, possibly followed by the rapid passage of a frontal wave cyclone.
The cyclonic variants are characterized by a cyclone travelling across the Czech Republic to the north-east or south of the Czech Republic to the east.