48 
Fig. 6.12.1. Route of the stormy depression, pressure pattern and wind field over the Baltic 
Sea on 21 February 1993, 12 UTC 
Flowever, another active depression quickly moved in from the Norwegian Sea, tracking 
across Scandinavia towards the southeastern Baltic Sea where, between 00 and 09 UTC on 
20 February, it slowed down and backed eastwards, reaching the Lithuanian coast around 
noon. Similar to the day before, a high pressure ridge over Scandinavia developed in the rear 
of this low. In the cyclonic wind system generated by the low, southwesterly to westerly 
winds of 6-8 Bft were recorded over the western and southern Baltic Sea in the afternoon of 
20 February. In the night of 21 February, the winds developed into a northerly storm which 
soon, shortly past 09 UTC, veered NE and reached 7-9 Bft. The zone of NE storm first 
spread across the northern Baltic Sea and Baltic Proper and, towards noon on 21 February, 
also covered the western, southern and southeastern Baltic Sea. The northerly air flow 
brought cold Arctic air into the region, causing winds to become more gusty. In the late hours 
of 21 February, the pressure gradient weakened over Denmark, Kattegat and the western 
Baltic Sea, and the depression filled and moved towards Lithuania. In consequence, the 
storm over the entire southern Baltic Sea decreased to 8-6 Bft, and later 7-5 Bft, in the early 
hours of 22 February. 
Late on the same day, the pressure gradient steepened again over the western Baltic Sea 
due to a ridge of high pressure spreading eastward from the British Isles. Northeasterly 
onshore winds strengthened again over the western parts of the coast and stayed there until 
the early hours of 23 February, after which they decreased slowly. 
Hydrological response of the sea level 
The described variation of the meteorological pattern resulted in a series of fluctuations of 
the water surface at the southern coasts of the Baltic Sea. 
The first wind set-up was preceded by a decrease of sea levels about midday on 19 
February. Water levels began to rise late on 19 February and rapidly reached their maxima, 
with extreme values not exceeding 590 cm, however. 
When the northerly wind backed to alongshore directions and abated, water levels also fell 
slowly. The rate of decrease was soon accelerated considerably by a southwesterly storm 
which developed over the western and southern Baltic Sea in the afternoon and night of 20 
February. The lowest value of nearly 460 cm was reached in Wismar; in the central part of 
the coast, sea levels oscillated around 500 cm (Fig. 6.12.2.).