The first thumbnail of the weather sounding showed lots of moisture at all levels in the atmosphere creating the photographed heavy-looking clouds. Combined with lots of wind shear due to a cold front which had passed, produced beautiful undulations (wave-like features) within the stratocumulus clouds. Such clouds are very common in the Winter season and their wave-like feature was due to increased wind speed with altitude. Despite the clouds looking full of rain, it only produced drizzle in the area which was later followed by steadier rain and a thunderstorm which did not affect any landmass. The surface pressure chart is shown in the second thumbnail while the third shows an upper trough at 500mb height which passed very quickly over Malta.