The causes of supercell development with tornadogenesis on 30th August 2003 – A case study

Abstract

A supercell storm with tornadogenesis in the afternoon hours of the 30th August 2003 in NW Croatia is studied. As was seen from radar and satellite material the cell developed in Slovenia and crossed into Croatia, where interacting with favorable wind patterns (indicated by high SREH and vertical wind shear) it evolved into a supercell. Macroscale forcing was found to be lacking. On the other hand, the pattern, characterized by a pronounced thermal ridge and a baroclinic boundary associated with it, was favorable for supercell generation as has been seen in several studies in the USA. Mesoscale forcing was also enhanced by the existence of the jet stream and outflow boundaries from previous convection associated with a night-time cold front passage. Several severe storm and stability indices were tested for this case and it has been found that they generally did not correspond to the severity of the convection that took place.