MSG IR10.8 imagery with tendency of surface pressure and wind: time sequence

18th August 2004: 06UTC
The front that transformed later to a squall line arrived at 06 UTC the western parts of France. However, the cloud tops do not extend to the tropopause (cloud top temperatures above -60°C). A small area with decreasing surface pressure can be seen in the forefield of the front. The wind barbs near the Atlantic Coast indicate a confluent streaming.

18th August 2004: 09UTC
The area of falling surface pressure broadened. No deep convection occurred.

18th August 2004: 12UTC
The dipole structure of the surface pressure tendencies moved further to the East and the brightness of the cloud band increased. Although we recognise convective structures we do not observe convection up to the tropopause and beyond.

18th August 2004: 15UTC
The dipole structure moved to the East and covered Eastern France, the Benelux-States and most of Germany. The amount of pressure tendencies did not change significantly. However, the blue coloured areas (cloud top temperatures below -60°C) indicate that the squall line intensified (cloud tops extended to the tropopause or beyond).

18th August 2004: 18UTC
The convergence zone arrived over East France and West Germany where the most intense convection occurred (cloud top temperatures below -60°C). There was an area of intense rising pressure over Central France with rises of up to 5hPa/3h. At the forward edge of the cloud band the pressure was falling by up to 2 hPa/3h.

18th August 2004: 21UTC
The area of falling surface pressure covered most of Germany. However, the rate of fall was decreasing as was the intensity of convection. The imagery show only a few small areas with cloud top temperatures below -60°C.

19th August 2004: 00UTC
Ahead of the squall line the pressure was still falling at up to 2 hPa /3hr. To the rear the pressure was rising by 2 hPa/3h. The convergence zone extended along about 11 to 12°E. Deep convective clouds existed only west of Denmark and over Southern Sweden. Over Denmark moderate to heavy rain was reported however, some areas reported no precipitation (details in physical background).