Re-analysis of a high-end severe weather event on 18 August 1986.
|Year of publication||2013|
|MU Faculty or unit|
|Description||On this date, an extraordinary severe weather event was observed over the Czech Republic and some other countries (e.g. Germany or Northern Italy) featuring intense hailstorms. In case of the Czech Republic, a single supercellular thunderstorm managed to produce a 230 km long hail swath with many reports of very large hail (up to 12 cm in diameter) and severe wind gusts. This resulted in an extreme damage with some settlements losing every single roof, and also several casualties. Even though a relatively thorough analysis has been done shortly after the event (Pavlik - Kakos - Strachota, 1988), little has been known in those times about the supercell or large hail prediction. Thus, we would like to shed more light on the environmental conditions (using the ingredient-based methodology), which allowed for perhaps the most intense hailstorm in the modern history of the Czech Republic. Large scale conditions will be assessed using the ECMWF reanalysis data with the horizontal resolution of 0.5 degrees. More regional and detailed analysis will be based on the run of COSMO model featuring 50 vertical levels and a horizontal resolution of 2.8 km. This case became well-known also from the satellite perspective, because hailstorm exhibited very significant cold-U feature with a "plume" of cirrus extending over its "warm" interior part (Setvak - Doswell, 1991). In the light of a new research that has been done on the storm-top characteristics, we return to this case and discuss its significance. Eventually, this study should mostly serve as a re-analysis of the event from the forecaster point of view, contrasting the low and high-resolution model output and their ability to reproduce severe storm environment. We also point to the nowcasting possibilities (spatial-temporal resolution of the data) that were available at that time versus the current situation.|