Formation of cumulonimbus with heavy rain (occurring offshore) due to the approach of an upper-level low towards the Maltese Islands as indicated in the fourth thumbnail. The first thumbnail shows a close-up photo of the cumulonimbus cloud whilst the second thumbnail indicated cumulonimbus incus cloud formation taken earlier on the day. The third thumbnail of the weather sounding shows an unstable profile but with relatively drier air and lack of wind shear but still good for cumulonimbus cloud formation given the water heat content trigger as trigger. The fifth thumbnail is the visible satellite image showing a line of clouds to the NW of the Maltese Islands, probably a squall line. This line of clouds seemed to have been generating wind giving the ideal conditions for yet another sub-type of cumulonimbus being the arcus sub-species. Having said this, the surface pressure chart was not showing any note-worthy features over our Islands. Photos of this cloud and further explanation were shown in the previous picture.