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5.4 Conclusions 
The above grouping of typical pressure patterns is not meant to be a classification of 
meteorological situations based on the similarity of their impact on sea levels along the 
southern Baltic coast. Such groups cannot be precisely defined because meteorological 
conditions in the area are continually changing, and it would be impossible to find two 
identical pressure patterns even in an area as limited in extent as the Baltic Sea. Therefore, 
also the frequency of occurrence of storm events of a particular group can only be roughly 
estimated. During the 25-year period studied, about 40 percent of all storm surge events 
were caused by strong northerly air flow over the Baltic Sea, with high - or rising - 
atmospheric pressure over Scandinavia and a depression moving southwards near the 
eastern boundary of the Baltic Sea (type 6.2.1.). About 55 percent of the storm surges were 
caused by gale-force winds developing at the rear of atmospheric depressions moving 
eastwards across southern Sweden, the southern basins of the Baltic Sea, or across land 
close to the southern coast (type 6.2.2.). Only about 5 percent of all storm surge events 
analysed were due to a strong E air flow over the southern Baltic Sea along the southern 
edge of an anticyclone over northern Russia and Scandinavia. During some of the easterly 
storm surge situations, cyclonic circulation was caused by a depression over the mainland 
which was slowly travelling northwards and encountered blocking high pressure over the 
Baltic Sea. 
Summarising the above, it should be noted that - irrespective of the path of an approaching 
depression posing a storm surge threat - sea levels in a particular section of the coast react 
primarily to the impact of the wind on the near-shore coastal waters and depend strongly on 
the local morphometric and hydrological conditions. Any type of onshore wind may lead to a 
considerable rise of coastal sea levels if it is strong enough and has a long fetch, both of 
which are factors extending the duration of the storm. The problem is the determination of 
the threshold values for these factors.