Factors affecting the Adriatic cyclone and associated windstorms

This paper presents results of numerical experimentation of the orographic influence of the Dinaric Alps and the Apennines and of moist processes on the Adriatic cyclone and associated windstorms. The case of 28 March 1995, characterized by an intense Adriatic cyclone and damaging windstorms, is simulated using the high-resolution hydrostatic model ALADIN. The model successfully reproduced the formation of the cyclone in the northern Adriatic and its fast movement along the basin to the south-east. The strength of associated winds, particularly severe jugo and bora along the eastern Adriatic coast, are well reproduced. Sensitivity studies confirmed that the Adriatic cyclone is an orographic lee cyclone with respect to the Dinaric Alps, although it originated as a cyclone in the lee of the Alps. The influence of the Dinaric Alps is visible in a high-low couplet over the orography due to the orographic blocking and severe winds along the coast behind the cyclone. The intensity and duration of Adriatic bora storms depend not only on a cold air supply over the Dinaric Alps but also on the lee side effects due to the mesoscale cyclone in the Adriatic sea. In addition, the appearance of the 'twin cyclone' in the Tyrrhenian sea is simulated as a realistic feature, induced by the Apennine's orography.