Brzovic, Nedjeljka (Meteorological and Hydrological Service of Croatia)
Zagar, Mark (Hydrometeorological Institute of Slovenia)
The northern Adriatic area (together with the Po valley), enclosed between the Alps, Apennines and the Dinaric Alps, is a region where the orographic effects are of the great importance in controlling the weather, and appears very favourable for cyclogenesis. Severe weather conditions are often related to the development of the Adriatic cyclone, accompanied by strong winds bora and jugo and intensive convective development along the eastern Adriatic coast. Only in 1995. severe storms are responsible for almost 70% disaster damages in Croatia. In the coastal regions of Slovenia and northern Italy, high tides due to the low air pressure and jugo wind frequently cause additional problems, apart from the harmful weather itself.
Synoptic climatology of the Adriatic cyclones in the last two years has served as a database for the investigation of the high resolution ARPEGE/ALADIN model capability to resolve local features associated with the cyclone development, specially those under the prevailing orographic influence. Among many cases which have occurred during the past period several representative ones have been chosen for a further study. These include examples of good and bad forecast, together interesting for studying the reasons of differences in the forecast quality.
Detailed analysis is undertaken to follow the life cycle of each of the chosen cases, and especially the reasons why in some cases the forecast failed. Interesting situations include also those with cyclonic paths different from the usual one: although the Adriatic cyclone is usually subject to the effect of channalization near the Dinaric Alps, there are some cases when a cyclone travels over the Dinaric Alps and the Balkan peninsula.
Correct prediction of such situations is particularly interesting. The main objective of the present work is to offer a closer insight into the model physics using different sensitivity studies, like the model's sensitivity to boundary conditions, orography and roughness length representation. Details of the convective parametrization are specially investigated since it has been clarified that the closure assumption of the convective parametrization is crucial factor for success (or failure) of Mediterranean cyclones simulation in general.
Furthermore, our work is aimed to the very first efforts in the direction of the objective verification of precipitation.