Synoptic situation
Several convective cells can be recognised embedded into the frontal system. On 20th August most of them can be spotted over Northern Africa and especially Tunis. These are the locations where thunderstorms are likely to occur. Over Switzerland and Austria some CBs are also embedded. More important to the case study in these set of WV images are the 'dry slots'. At 21st of August 2005 at 00.00 UTC two of these dark slots can be recognised. One over Gibralta and Northern Africa and a second one over France, Spain into the bay of Genoa. The dark slots mark the locations where stratospheric air is deepening. They indicate cyclogenesis. Most of the convection developing is seen near to these dark stripes. Deepening of stratospheric air from above causes the atmosphere to become less stable. When moisture is then added from below it is ideal for CBs to develop.
8 January 2005/00.00 UTC - Meteosat 8 WV6.2 image
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