SYNOPTIC AND MESOSCALE ANALYSIS OF HAILSTORMS OVER CROATIA ON 22 AND 23 JUNE 2007

A case of severe convective development affecting Croatia on 22 and 23 June 2007 is analyzed by means of synoptic material, satellite, radar and lightning data as well as hailpad data and hail observations. The development occurred during the passage of a cold front in strong upper-level south-westerly flow, bringing warm and humid air from the West Mediterranean. The onset of convection was triggered by the orographic lifting on the islands and later on the Dinaric Alps. A supercell developing in the North Adriatic split into two cells due to strong vertical wind shear and veering of the wind in the lowest 3 km. The right-moving cell with cyclonic rotation was longer living and the left one died out. Large hail was reported along the path of the cell. Later on, convective cells developing over the continental part of Croatia were of lower intensity, but still bringing hail of the hazelnut size. Hailpad measurements and hail observations show the distribution of hail in time and give the information about the sizes of hailstones. Aladin meso-scale model performance is tested for the development in the North Adriatic, showing that the model could successfully reproduce the environment and the conditions for severe convective development, however underestimating the precipitation amount

FLASH-FLOOD IN PULA IN THE NIGHT BETWEEN 24 AND 25 SEPTEMBER 2010

A flash-flood event in the western part of Croatia during the night between 24 and 25 September 2010 is analyzed by means of satellite, radar, lightning and rain-gauge measurements and NWP model data. A relatively rare positioning of two Mediterranean cyclones induced a strong convergence zone in the Northern Adriatic. One of the heavy precipitation episodes stroke the town of Pula and the surrounding Istrian inland resulting in 176 mm of rain in less than 7 hours, the highest daily amount ever measured in Pula. Operational 8 km resolution hydrostatic ALADIN model forecast satisfyingly the existence of twin cyclones and precipitation maximum over the sea. The processes that led to the development of the secondary maximum inland were explored using the 2 km resolution non-hydrostatic ALADIN model