44 
of 7 December, successive fronts crossed the coast. The northwesterly storm continued to 
veer and temporarily reached 12 Bft (Fig. 6.10.1.), after which it decreased slowly. As the low 
pressure centre moved eastwards, filling very slowly, and the anticyclone over Scandinavia 
persisted, the pressure gradient between the two centres remained steep enough to maintain 
strong winds over the Baltic Sea for many hours. However, between 12 UTC on 7 December 
and 6 UTC on 8 December, the atmospheric pressure in the region west of Denmark and 
over the western Baltic Sea decreased as a minor local cyclonic disturbance began forming 
in the region of Kattegat and southern Sweden. This led to initially decreasing winds, which 
then backed SW again and increased, blowing as a strong offshore wind over the western 
Baltic Sea for several hours. 
Fig. 6.10.1. Route of the stormy depression from 00 UTC on 6 December 1989 to 12 UTC on 
7 December; pressure pattern and wind field at 06 UTC on 7 December 1989 
Hydrological response of the sea level 
The southwesterly offshore storm on 5 and 6 December caused water levels to decrease 
slowly to 450 - 470 cm. This effect was more pronounced in the western part of the coast. In 
the central part of the coast (Kotobrzeg), the water gauge did not indicate levels below 489 - 
490 cm (between 07 and 11 UTC), while in Wismar the minimum level recorded only about 
10 hours later, between 16 and 17 UTC on 6 December, was as low as 448 cm. These 
differences increased as the pre-frontal zone of strong southwesterly wind crossed particular 
sections of the coast. Culmination was reached on 7 December between 11 and 15 UTC, 
depending on the position of the tide gauge. Maximum values varied between 633 cm in 
Wismar and 605 cm in Swinoujscie (Fig. 6.10.2.).