Most  severe  negative  surges  on  the  southern  Baltic  Sea  coast

59

December  2001

Wismar  —•—Warnemünde  Sassnitz  »  Swinoujscie  —  —Kotobrzeg  MSL
Fig.  5.18.  b  Variations  of  sea  level  decrease  during  the  storm  surge  of  20  to  21  December,  2001

5.19.  January  2005
Meteorological  situation
Late  on  7  January,  an  active  low  pressure  centre
formed  west  of  Ireland  in  the  westerly  air  flow
over  Europe.  In  the  course  of  8  January,  the  low
crossed  the  Norwegian  Sea,  southern  Norway
and  central  Sweden,  deepening,  and  reached  the
Aland  Islands  at  00  UTC  on  9  January,  with
961  hPa  measured  in  its  centre.  At  03  UTC,  the
centre  entered  southern  Finland  and,  slowing
down,  meandered  toward  the  area  north  of  Lake
Ladoga,  where  it  arrived  around  12  UTC.  From
there,  the  low  veered  southeast,  filling  soon.
The  frontal  system  associated  with  the  low  initially ­
  did  not  influence  the  wind  direction  as  it
crossed  the  Baltic  Sea  region,  but  behind  the
warm  front  tracking  across  the  Baltic  Sea  in  the
morning  of  7  January,  the  strong  westerly  wind
soon  backed.  On  8  January,  as  the  fast  moving
centre  deepened  quickly  and  the  pressure  gradient ­
  was  steepening,  the  southwesterly  storm
gradually  increased  in  severity,  reaching  10  Bft
between  21  UTC  on  8  January  and  03  UTC  on
9  January  as  the  occluded  front  advanced  east.
The  strong  wind  later  veered  west  and  gradually
weakened  towards  evening  (Fig.  5.19.  a).

Hydrological  response  of  sea  level
In  spite  of  the  strong  winds,  sea  levels  remained
close  to  the  mean  values  until  around  noon  on
8  January.  They  began  to  fall  around  18  UTC,
after  the  strong  wind  had  veered  to  southwesterly ­
  directions.  In  response  to  the  heaviest  phase
of  the  west-southwesterly  storm  behind  the
occluded  front,  levels  remained  below  380  cm
from  00  UTC  to  10  UTC  on  9  January  in  the
western  part  of  the  coast.
The  recorded  minima  were:  352  cm  in  Wismar  at
07  UTC,  379  cm  in  Warnemünde  and  403  cm  in
Sassnitz,  both  at  about  04  UTC,  and  410  cm  in
Swinoujscie  at  05  UTC.  The  variations  of  sea
level  values  between  12  UTC  on  8  January  and
12  UTC  on  9  January  in  Kotobrzeg  could  not  be
recorded  due  to  a  malfunction  of  the  gauge.