Deep, intense low pressure passes over Scandinavia

By Anna Eronn (EUMETSAT)

Already at the beginning of the week commencing 23 November 2006, i.e. three to four days before the storm, numerical weather prediction forecasts indicated the formation of an intense low pressure system. This was the first storm for Scandinavia this winter season and, comparing with the winter season 2005–2006, this was more severe than any storms last year.

On 26th the low pressure system intensified over the North Sea then moved east and approached Scandinavia. At the same time its frontal system with rain moved north to northeast over Sweden, and from central Sweden northwards the precipitation fell as snow. During the night to 27th the low pressure system moved northeast over Sweden and the weather started to cause problems.

South of the low pressure centre, over Denmark and southernmost Sweden, and especially along the coastal regions, wind gusts increased up to storm force (33m/s) with mean wind speed up to 24m/s. Buoy data reported from the Skagerrak indicated significant wave heights (4.4m) with maximum seas of 6.5m. The strong winds over land felled many trees which then cut electricity supply for thousands of homes.

But the main problems affected central and northern Sweden due to the heavy snowfall, up to half a meter in places and, at the same time, with strong winds. Along the Swedish north east coast winds up to 20m/s and temperatures just below zero degrees resulted in a large amount of wet and heavy snowfall. For this area SMHI had announced the highest severity of weather warning, namely class 3.

The image below is a so-called Airmass RGB product where airmass characteristics can be seen. The RGB composite combines four channels, the two water vapour channels WV6.2 and WV7.3 and also the IR9.7 and IR10.8 channels. In this image one can easily detect the PV (Potential Vorticity) anomaly associated with this intense low pressure system as a large area of bright red over Scotland and the North Sea.

Additional content

Fog RGB (Polar Stereographic Projection) (27 October, 04:15 UTC)