Galvonaite, Audrone (Lithuanian Hydrometeorological Service)
The Mediterranean cyclones amount to 25-27 per cent of all cyclones acting over Lithuanian territory. In most cases the southern cyclones are being observed in Lithuania in the second half of winter and in the begining of spring, i.e. from January till April. Three types of the Mediterranean cyclones have been separated: 1st- cyclones born in the Mediterranean region, migrating straightforwrad towards Lithuania, 2nd- cyclones migrating straigthforward northward, more westward of 20th meridian. They act on Lithuania by their eastern border. The beginning of action is about after 25 h, when the cyclone center is 500 km from Vilnius, 3rd- cyclones with the north-east component. They act on Lithuania by their north-west border. The begining of action is about 38 h after cyclone formation. The cyclones of this type reach Lithuania by their northward far-stretched fronts and their waves. The Mediterranean cyclones otherwise than the Atlantic (western) ones in most cases are deepening not far from Lithuania, their frontal activity becoming more active, vertical currents increasing. All this results in the sudden changes of weather, for instance in the strong wind, poring rain in summer. The amount of precipitation of several hours often exceeds the monthly mean. In winter the southern cyclones cause strong blizzards, ice storms, ice accretions and hurricane winds breaking trees, falling poles.
Observed fluctuation of temperature sometimes reach 10░C and more. The Mediterranean cyclones are being anticipated in Lithuania with a certain anxiety for their sufficiently difficult forecasting and also for possible consequences when they pass. In the work is being analysed more in details the influence of individual cyclones on Lithuania, also illustrations are being presented.