56
Negative Surges in the Southern Baltic Sea
December 1999
Wismar —•—Warnemünde Sassnitz ■» Swinoujscie — — Kotobrzeg MSL
Fig. 5.16. e Variations of sea level decrease during the storm of 6-7 December 1999
5.17. November 2001
Meteorological situation
On the days preceding the surge, as northwest
erly air flow prevailed over the Baltic Sea, a de
pression developed near the southeast coast of
Greenland. Initially tracking east, the low pres
sure centre then moved quickly southeastward
toward northern Norway.
It then tracked across the northern part of the
Gulf of Bothnia and central Finland, which it left
late on 15 November. Continuing in southeastern
direction, the low pressure centre crossed Lake
Ladoga, filling in the area southeast of this basin
around noon on 16 November.
As the pressure trough associated with this cen
tre moved across Scandinavia and the Baltic
Sea, the moderate northerly winds prevailing in
the western Baltic backed west, then southwest,
as wind speeds increased. Early on 15 Novem
ber, winds reached 7 Bft in the entire Baltic Sea
region and soon increased to 8-9 Bft. Between
14 and 22 UTC on 15 November, the cold front
crossed the southern Baltic coast, first in the
east, and about 9 hours later in the west. Behind
the cold front, winds veered northwest in on
shore directions, calming only over the western
and partly over the southern Baltic Sea, while the
central, northern and eastern regions of the Bal
tic remained under the influence of stormy north
erly winds (Fig. 5.17. a).
Hydrological response of sea level
When early on 15 November the low pressure
trough was moving southeast, the stormy winds
backed in offshore directions, causing sea levels
to fall gradually and nearly simultaneously along
the whole southern coast, first at the eastern
most water gauges.
Thus, the minimum value at Kotobrzeg was
456 cm at about 15 UTC, at Swinoujscie 421 cm,
and at Sassnitz 407 cm, both around 18 UTC. At
Warnemunde, 396 cm was measured at about
20 UTC, and at Wismar 365 cm at 21 UTC
(Fig. 5.17. b).
