RGB combination of Meteosat-8 images channels 1, 3 and 9

The RGB image shows that the bright area in the front of the frontal cloud band is formed mostly of the high cloud which are blue in the image. Behind the high clouds, thick part of the frontal cloud band is identified by the violet colour and the lower cloud tops at the rearward part of the frontal cloud band by more gray or yellowish colours.

The separation of the cloud types is much better seen seen in this image. The area of intensification is identified by violet colour, and that is exactly the area where the percipitation occurred. Notice also the snow on the Alps and the Pyrenees.

Similar like 3 hours before, the intensification of cloudiness goes on. Area of high, thick clouds within the frontal cloud band identified by pink colour, represent the intensification in the left exit region of the jet streak.

The front has moved towards south-east. The intensification of frontal cloud band is still present. The clouds form a spiral-like form. Behind the frontal zone convective development can be seen over Austria and Slovenia as a result of the cold advection. Some convective development can be seen also over Croatia.

The progressing of the system to the south-east goes on. What strikes the most in this image ia a great amount of cells over the whole region from Mediterranean to Finland. This convectice development is a result of a very strong cold advection from the north.

Comparing this image to the one in the WV channel shows that the reason that there are low cumuli (yellowish) and highly developed convective clouds (violet) can be found in the fact that there is a dry area in the upper levels behind the frontal zone. The cold and dry, probably stratospheric air, overruns the rear part of the frontal cloud band. Therefore the lowering of the cloud tops can be seen in the rear part and the much higher cells in the leading part of the frontal zone, especially in the intensification area.