At 06 UTC on 24 November, WAVEWATCH III was forecasting a large zone of “very rough to high” seas approaching the position of the Polarstern (the white dot) from the west. The forecast probable wave height was approaching 5.5 m (increasing to 10 to 12.5 m in the area indicated in brown). By 09 UTC, the Polarstern was expected to reach the edge of this area.
At the 09 UTC synoptic hour on 24 November, the Polarstern was reporting wind waves of 4.5 m due to the increased wind activity and a swell of 3.5 m. This would lead to expected total seas of up to 8 m.
The wind speed continued to increase through the morning, and the pressure tendency showed a decreasing trend as the vessel was still approaching the front.
By 15 UTC on 24 November, the vessel was reporting severe gale force west-northwesterly winds (41 to 47kt) and wind waves of 9.5 m. These conditions compared well to the conditions forecast by WAVEWATCH III for that hour and position.
In the period between the intermediate and main SYNOP reports, from 15 to 18 UTC on 24 November, there was a marked change in conditions. This leads us to speculate that this was when the vessel moved through the surface cold front. The observations that support this conclusion include the following.