Formation of marine cumulonimbus clouds to the southwest of Malta because of the passage of a line of bad weather (solid black line in the surface pressure map – second thumbnail) towards the south generating instability around the Maltese Islands as indicated on the weather sounding of the third thumbnail. The first thumbnail shows an unzoomed image of a mature cumulonimbus (Cb Incus) as such conditions allowed instability to be released into the atmosphere and the slight Convective Inhibition was easily overcomed by the warm sea temperature. On the day, lightning activity was also observed offshore. The rain radar indicated isolated but barely-moving heavy rain showers due to lack of steering wind at all atmospheric levels.