Geopotential height 1000 hPa

In the initial stage of the case study the main feature in the surface chart (the geopotential height field at 1000 hPa) is high pressure over the west Europe and Atlatic. The shallow low is over the Baltic sea and the cloud band is associated with the occlusion. The other cloud band, east of the Great Britain, on the leading side of the anticyclone and on the leadig side of the upper level ridge (see also AT500 fields), is connected to the frontal system which will continue to move to the south.

The situation is similar to the one a six hours before. The surface trough over Baltic sea is accompanied by frontal cloudiness on the eastern and southern side of the Scandinavia.

The cloud system is moving from north-west to the south-east on the front side of the anticyclone with pronounced intensification. The situation in the pressure field remains unchanged.

The frontal zone is moving further to the south-east. The darker clouds on the leadig side of the surface trough are connected with the occlusion.

As before the geopotential height field at 1000 hPa shows a through over the north-east Europe and a surface ridge with the centre over Great Britain. The cold front is over south Germany and Austria with further intensification of clouds.

The situation in the surface pressure field (geopotential height field at the 1000 hPa) cannot explain the mesoscale features observed in the satellite imagery. For example, the comma cloud feature starts to form over Hungary, behind the frontal zone, but this is not recognized in the surface field.

The new shallow low is formed over the south-east Europe and there is a indication that another one will form in the Geneva bay. The cold front is reached Croatia and a cold advection behind can be seen like a cellular cloudiness in the satellite image.

The high pressure is spreading over central Europe, and the frontal system is moving further to the south-east. The surface trough over east Europe is associated with the deep through in the upper level as can be seen in the 500 hPa height fields.

The cold front is slowly dissipating, but over the south Italy and the south Adriatic the comma cloud structrue has formed. Again, it is not indicated in the surface pressure, but there is a deep trough in the upper level which is mentioned in the image six hours before.