Surface Observations, Time Sequence: 27 July 2006

In this chapter hourly observations of total cloudiness and significant weather are presented. For a better understanding wind barbs are shown, too. At 12 UTC, thunderstorms are already reported over western and central Germany which correspond to convective cells in the IR image.

During the last hour new convective cells developed and in accordance to that more thunderstorms were reported. At this time, we can identify two convergence zones over western and central Germany, in good correspondence with the satellite image.

At 14 UTC, the thunderstorms' density continued increasing. They started to merge to one big convective complex that can be seen from the merging of cirrus shields and the formation of one North-South oriented surface wind convergence.

This image exhibits more clearly the squall line: line orientated highly extending clouds and thunderstorms as well as one surface wind convergence. Compare also the lightning detection from 15.00, 15:30 and 16:00 UTC presented in the next chapter.

Thunderstorms are concentrated along the north-south oriented squall line covering Germany. The image gives hint to a possible new development in the forefield of the main convective complex extending from eastern Germany to the Czech Republic. We find new convective cells and in particular a convergence of surface winds. This development should be monitored more carefully due to the difficulty of estimating the influences (diurnal cycle and dynamical forces).

At 17 UTC, the linear structure of the squall line extending from northern to southern Germany is still clearly to be seen. However, no significant movement happened during the last hour. The new convective complex moved further to the East, however, weakening (see also IR-Enhanced).

Thunderstorm activity slows down throughout the afternoon. However, no clear squall line structure can be detected from the wind barbs.