22 
Trzebiez during those days varied from 0.1 to 0.4°C. On 22 February, after an intrusion of 
cold Arctic air extending south as far as Central and Southern Europe, a high formed there 
which oscillated between the British Isles, south-eastern Europe and Scandinavia until the end 
of the month. Under the prevailing anticyclonal conditions, the air cooled gradually. Around 
Szczecin Lagoon, the daily means decreased to about -4°C, with minima ranging between -4° 
and -9°. A snow cover formed again which was 8 cm thick on 20-21 February'. The water 
temperature in Trzebiez fell to 0° on 26 February. 
March 
In March, the situation was largely unchanged at first. The anticyclone stabilised over 
Scandinavia where it remained for 14 days, causing frosty and dry air from the north-east and 
east to flow across the Baltic Sea. With anticyclonal conditions, predominantly light winds, 
and radiative cooling in clear nights, the air temperatures fell: daily means in Trzebiez ranged 
between -5° and -10°C, minimum temperatures were below -10°C in the majority of cases. In 
(Ewinoujoecie the grass minimum temperature was below -16°C from 9 to 15 March (the 
lowest value recorded was -20.3°C). The snow cover thinned gradually. On 15 March, the air 
flow changed to westerly, bringing mild maritime polar air masses. Temperatures around 
Szczecin Lagoon increased to positive, they did not. however, exceed 2°C until 22 March. 
Daily maxima varied between 2.5° and 5°C. Only patches of snow cover remained in 
Swinoujscie. Water temperatures in Trzebiez rose above 0°C as early as 15 March, and 
increased gradually to 1°C on 26 and 4.5°C on 31 March. From 23 to 30 March, daily means 
varied between 2.5 and 9.6°C. The day of maximum temperature (13.1°C) was preceded by 
strong southerly and south-westerly winds. 
April 
The first 15 days of April had mean daily air temperatures around 5°C. Minimum temperatures 
were positive, except on the first day of the month. On 9 and 10 April, heavy rain was recorded 
at all stations around Szczecin Lagoon. Water temperatures increased gradually, from 4.6°C in 
the first days of the month to 10°C on 17 and 15.4°C on 30 April. 
Table 2.7. Air temperatures and variations from the normal value (1961-1990) 
in Szczecin Lagoon in winter season 1986/87 
November 
December 
January 
February 
March 
mean 
max. 
min. 
mean 
max. 
min. 
mean 
max. 
min. 
mean 
max. 
min. 
mean 
max. 
min. 
Swinoujscie 
6.9 
13.0 
0.9 
2.2 
11.7 
-4.6 
-6.2 
4.1 
-19.0 
-0.8 
6.3 
-9.7 
-1.3 
12.8 
-12.3 
divergence 
2.2 
1.1 
-5.6 
-0.7 
-3.9 
Trzebiez 
6.5 
12.9 
-1.2 
1.9 
11.3 
-5.8 
-7.9 
4.1 
-26.2 
-1.1 
6.9 
-11.9 
-1.7 
13.1 
-14.0 
divergence 
2.2 
1.1 
-6.9 
-0.7 
-4.3 
Szczecin 
6.6 
13.4 
-3.0 
2.0 
12.5 
-6.6 
-7.9 
4.4 
-30.0 
-0.9 
7.3 
-13.5 
-1.0 
13.0 
-13.7 
divergence 
2.2 
1.2 
-6.fi 
-0.5 
-4.0 
Table 2.8. Water temperatures and variations from the normal value (1961-1990) 
in Szczecin Lagoon in winter season 1986/87 
November 
December 
January 
February 
March 
mean 
max. 
min. 
mean 
max. 
min. 
mean 
max. 
min. 
mean 
max. 
min. 
mean 
max. 
min. 
Mi^dzyzdroje 
7.1 
8.1 
5.3 
3.7 
5.6 
1.3 
-0.1 
1.6 
-0.5 
-0.2 
0.1 
-0.5 
0.2 
2.1 
-0.5 
divergence 
0.7 
1.0 
- 1.2 
-1.2 
-2.2 
Trzebiez 
6.6 
7.8 
5.6 
2.9 
5.8 
Ü.2 
0.1 
0.4 
0.0 
0.2 
0.4 
0.0 
0.8 
4.5 
0.0 
divergence 
1.2 
0.8 
-1.0 
-1.1 
-2.6 
Szczecin 
7.3 
8.8 
6.6 
3.7 
7.6 
0.3 
0.3 
1.4 
0.0 
0.5 
1.0 
0.2 
1.8 
5.5 
0.1 
divergence 
1.1 
1.1 
- 1.2 
- 1.3 
-2.5