Formation of cumulonimbus cloud over southeast Sicily as seen from Valletta in Malta. The localized Sicilian storm cloud had formed due to that island`s sea breezes clashing in a point of convergence (4th thumbnail) under a weak and broad upper-level trough (last thumbnail) following heatwave conditions. Such Summer thunderstorms are not rare in the Mediterranean on major Islands. The problem for storm clouds to develop over sea areas in Summer is the lack of forcing mechanisms such as weather fronts. The first attachment looks at the very same cloud from a wider perspective while the second attachment shows another distant storm cloud taken on the previous day with similar weather conditions in the area.