Ocean waves crashing on rocks

Record waves in the Baltic Sea

11 January 2017 06:00 UTC–12 January 12:00 UTC

Ocean waves crashing on rocks
Ocean waves crashing on rocks

On 12 January 2017 an intense low generated record high waves in northern parts of the Baltic Sea. Waves up to 14m were observed, equalling the previous record from December 2004.

Last Updated

04 October 2023

Published on

11 January 2017

By Linnea Rehn (SMHI)

On 10 January a wide low pressure system was located over the Norwegian Sea and a large high was located over Eastern Europe. This synoptic situation was responsible for a southerly to southwesterly wind over the Baltic Sea.

 Meteosat-10 Airmass, overlaid with 1000 hPa, 11 January 06:00 UTC
Figure 1: Meteosat-10 Airmass, overlaid with 1000hPa, 11 January 06:00 UTC
 Metop-A ASCAT 25 km winds, 11 January 06:00 UTC
Figure 2: Metop-A ASCAT 25km winds, 11 January 06:00 UTC

A secondary low over the North Sea deepened in the morning of 11 January and then moved northeastward over Scandinavia in the following 24 hours. The Meteosat-10 Airmass imagery from 11 January 06:00 UTC, overlaid with the 1000hPa fields (Figure 1), shows the position of this partial low — the red area represents dry descending stratospheric air.

The ASCAT 25km from Metop-A (Figure 2) shows wind speeds of about 40–45kts on 11 January at 19:40 UTC over the central part of the Baltic Sea (Figure 2). The record high waves were observed by a buoy managed by the Finnish Meteorological Institute a few hours after midnight (Figure 3). Figure 4 shows that Jason-2 measured a significant wave height of 22.18ft at 05:40 UTC near the Finnish buoy, which corresponds to about 6.8m. The red star in the figure indicates the approximate position of the buoy.

The high seas which occurred over the Baltic Sea on 11 and 12 January were very unusual, but the development of the storm low that affected the Baltic Sea was actually quite normal and it did not generate unusual high wind speeds over the Baltic Sea. Yet, despite this, record high waves were recorded. This small but intense low enhanced the southerly-southwesterly wind over the Baltic Sea and overnight, 11-12 July, the wind increased from strong gale to storm force.

 Northern Baltic Proper, 10–20 January
Figure 3: Significant Wave Height, Northern Baltic Proper, 10–20 January
 Jason-2, 3 and other satellites, 12 January, 00:00–12:00 UTC
Figure 4: Jason-2, 3, others, 12 hour collection of Altimeter Wave Heights, 12 January, 00:00–12:00 UTC

There are a lot of conditions for parameters that have to be met in order for significant waves of about 8m to build up over the Baltic Sea.

Due to the main low over the Norwegian Sea, a southerly-southwesterly wind was blowing over the Baltic Sea for at least 36 hours, and, for the last few hours before the record wave height was recorded, the wind speed increased to about 40–45kts.

The direction and duration allowed the wave height to build over a long distance — from the coast of Poland to the Archipelago Sea, east of Åland. So, in other words, the long fetch made it possible for the record wave to build.