Meteosat-8 WV6.2 Time Sequence: 24 Nov-26 Nov 2005

The cold front extended from Scotland to Norway and is also revealed by the WV image. Behind the front a distinct and broad dark area existed, indicating sinking air in the upper troposphere. Between Iceland and Scotland a sharp transition zone of brightness can be noticed. The jet stream can be located in this zone. The dark area is situated on its cyclonic side.

The broad dark area widened and moved to the Southeast.

The broad dark area kept widening while the cold front moved to the Southeast. Northeast of Scotland a cellular structure of brighter pixels indicates the development of the comma. However, the appearance of the comma is less marked than in the IR image because the 6.3 Micrometer water vapour channel covers only the upper and middle levels of the troposphere.

The position of the jet stream as well as the development of the comma structure in the cold air behind the front can be followed. Comma and cold front are clearly separated by a distinct dark stripe.

The comma is getting more distinct. The shallow moist area between the comma and the cold front shows some convective cells hinting at potentially unstable stratification.

The comma-like cloud structure is still darker than the bright cold front. However, this area kept growing and approached the cold front.

A weak wave bulge of the cold front can be seen in the area of merging (about 55°N/6°E). This situatiuon is typical for an instant occlusion.

At 21 UTC, comma and cloud front were only separated by a narrow black line (extending from the German-Dutch border, the North Sea to West Norway). During the next 3 hours it will merge.

The merging of comma and cold front took place. The typical appearance of an occlusion cloud spiral was reached. The jet was coming from a southerly direction behind the cloud band.

The cyclonic curvature of the occlusion spiral can be clearly seen. The centre of the low remained stationary for a long time.

The cloud spiral remained almost stationary over the Netherlands and Germany.

The situation over the Netherlands and Germany did not change significantly. The image reveals the cloud spiral more clearly.

The situation remained almost the same.

During the last 3 hours the surface low centre moved slightly to the West.

The surface low continued moving slowly to the West. The WV image shows dissipation of cloudiness within the cloud spiral indicating the end of this severe weather situation.

The WV image shows dissipation and southerly movement.

During the last 3 hours cloudiness over the Netherlands and West Germany kept on decaying.