Polar lows are mesoscale depressions which occur in the northern and the southern hemisphere far to the north and south, respectively, of the Polar Front. In the northern hemisphere they normally appear between October and April. They develop in small baroclinic zones, originating from old Occlusions or Arctic Fronts, and particularly in situations where arctic air flows out over relatively warm sea water. Generally, the lifespan of a Polar Low does not extend beyond two days and they appear mainly over sea. There are often problems forecasting them because of the lack of observations from the open sea. After landfall, Polar Lows disappear quite fast. Polar Lows can produce high winds, gusts and heavy snow showers, often in clusters.

In this case a Polar Low affected North-western Europe between the 27^th and 29^th of January 2004. The Polar Low moved along the Norwegian coast then southwards in a northerly flow and turned over the North Sea in the direction of the German Bight. Eventually the Polar Low made landfall over the border between the northern parts of The Netherlands and Germany.