Meteosat-8 IR10.8 Enhanced, Time Sequence: 3h, 29 February - 01 March 2008     

In this chapter we will investigate cloud structures using the Meteosat IR 10.8 channel with a colour enhancement in the temperature range from -24 to -64°C (see IR Enhanced legend) or click upon the key symbol (above). This helps us to interpret the information in the IR channel and will show more clearly following structures:

• High extending stratiform clouds
• Convection's intensity
• Frontal structures

At this time step we see stratiform clouds over Germany / North France and rain. Because this structure is not relevant we will not further consider it. The storm Emma was still west of UK/Ireland. It will be investigated more in detail.

Storm Emma approached UK. The cloud top temperatures (CTT) were between -56 and -60°C.

The clouds of Emma arrived over Ireland and parts of UK. We see high extending clouds (CTT: -60 to -64°C) and first indications of a split front (Northwest of Ireland).

The clouds of Emma covered almost entire UK and Ireland: We recognise high extending clouds that are connected to the Warm Conveyer Belt. The split front is just hitting Northwest England. Although the clouds did not extend to high levels moderate rain was partly reported.

Emma clouds were just hitting France, Benelux and Germany. However, the cloud top temperatures (CTT) increased slightly and temporary.

Emma clouds covered big areas and we see a bigger area of stratiform rain. In some areas the CTT decreased (violet areas). We recognise a cloud head over the North Sea and the dry slot east of Scotland.

Emma clouds covering big parts of UK and Middle Europe. Over the Channel high extending clouds (Warm Conveyer Belt) can be seen. The dry slot over the North Sea is clearly to be seen with light to moderate rain.

This image reveals a big cloud field with high extending clouds (CTT<-60°C). It moved fast to the East and arrived at the Benelux, North France and West Germany. Moderate and partly heavy rain was reported. The dry slot arrived at the southern parts of the North Sea. The model radiosounding (COSMO-DE, horizontal resolution 2.8 km, 50 levels) reveals the typical structure for split fronts (model radisounding). We recognise also first indications to convection (North Sea, along about 55°N) that can be seen as the onset of the convective line. The evaluation of the model sounding shows potential instability (e.g., KO=0) and a high storm relative helicity (565 m²/s²).

The hight extending cloud field moved very fast to the Southeast. Big parts of Germany and the entire Alpine region were influenced. We see more clearly the convective line over the North sea. radiosunding measurements (Schleswig, Emden, Bergen, North Germany) reveal (slight) potential instability, however, a very high storm relative helicity of about 800 m²/s² (not shown).

The cold front arrived the line "Poland-Germany-North France". The succceeding trough axis and the convective line at its frontal edge were over North Germany and the Netherlands (one report of thunderstorms, SW-Netherlands).

The cold front moved fast to southeast. Compact and highly extending clouds, rain, snow and some showers over East France and the Alps were reported. we still see cloud top temperatures of parly less than -60°C.

The convective line crossed West Germany. Although the cloud top temperatures were "only" about -40°C many thunderstorms were reported. This is typical for cold air convection.

The cold front crossed the Alps The succeeding convective line extended from the Baltic Sea to Southwest Germany and intensified during the last 3 hours. We see many reports of thunderstorms, partly with graupel/hail. One severe thunderstorm over South Germany (code-No 99, Neuburg, Danube) was observed.

The convective line hit the Alps and weakened. The CTT were "only" around -45°C. This image reveals also clearly the Föhn-effect: Stau clouds at the northern and central parts of the Alps and detached from that by a almost cloud free zone a cirrus shield over North Italy and parts of Austria.

The convective line weakened and left Germany.

The convective line and the preceeding cold front arrived in the meanwhile the Balkan Pensinula.

Both systems continued moving to the East/Southeast and weakened.

Both systems continued moving to the East/Southeast and weakened.