engleski

Violent Adriatic Windstorms

The most famous local winds on Adriatic are bora (bura), jugo (scirocco) and tramontana. The aim of the results presented is to improve the diagnosis and prediction of the bora and scirocco onset and severity. Knowledge of the mesoscale and large scale pressure patterns also increases the forecasting skill for surface winds in the region, especially in hazardous situations. Bora is strong, gusty, northeasterly downslope wind along the eastern Adriatic coast. Although recent bora investigation showed essential differences between bora behaviour in the northern and southern Adriatic, investigation of all severe bora cases reveal the multiscale nature of bora wind: the bora onset, its longevity and severity are closely related to larger mesoscale features, in particular those resulting from the interaction processes of synoptic scale flow with the Alpine massif and bora speed and direction are greatly influenced by local topographic shape. So, when discussing severe bora wind, we have to account that such windstorms are mostly subsynoptic features, strongly influenced by local processes and orography and are, therefore, very difficult to study by regular synoptic network. However, scirocco is mostly dominated by synoptic-scale events and, therefore, is much easily forecasted by larger-scale numerical models. The most severe cases are connected to the southern upper-level airstream over the Adriatic (ahead of a deep upper-level trough) during the presence of a Mediterranean cyclone. Such a situation is favourable for restoring a gradient-like stream, especially over the sea where surface friction is negligible. When severe scirocco situation is lasting for a several days one of the most welknown consequence, except the marine traffic disruption, is an unusual high sea level causing sometimes the flooding of Venice. Tramontana windstorms are especially dangerous for marine traffic because of development of high, ocean&#8211 ; ; ; like waves at the sea surface.

windstorm; bora; scirrocco; tramontana

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