Flash floods in Croatia from 2012 till 2022 – meteorological analysis

Flash flood forecasting and warnings remain highly challenging for many national meteorological and hydrological centers. In recent years, significant advancements have been made in hydrological and meteorological modeling, leading to rapid progress in forecasting capabilities. However, flash floods continue to cause substantial material damage and claim lives worldwide.

The purpose of this study is to gain a better understanding of the parameters and meteorological conditions necessary for flash flood events in various parts of Croatia, with the goal of improving prediction accuracy. Additionally, the authors emphasize that maintaining comprehensive databases of extreme events is essential for the further development of prognostic tools and warning systems. Recent studies also highlight the intensification of short-term precipitation, which, when combined with topographical features that favor heavy rainfall, underscores the importance of studying such events to mitigate the effects of climate change.

An ingredient-based methodology introduced in the 1990s suggests that the favorable combination of these ingredients can be identified across a wide range of synoptic and mesoscale situations. Therefore, it is crucial to analyze how these ingredients interact with Croatia's unique climate and orography. The use of a so-called flash flood checklist, integrating both meteorological and hydrological factors, can aid operational workflows and decision-making processes within national meteorological and hydrological services (NMHSs).

For the analysis of flash floods in the Republic of Croatia, 97 events from the period 2012 to 2022 were examined. A majority of the cases, 66 events (68% of the total), occurred in the coastal regions of Croatia. As expected, the largest number of events was recorded during the warm part of the year, with September standing out due to significant contributions from events in coastal areas, followed by June. Synoptic conditions were also analyzed, identifying two dominant weather types: the leading side of a trough with pronounced southwesterly flow and cut-off low. Thermodynamic conditions for 87 cases were assessed using upper-air sounding data, and a wide range of parameters and indices were analyzed and discussed.