Cb praecipitatio

A very isolated and heavy thundery rain shower falling on the SE of Malta including downdrafts over that area. A nearby location, Benghajsa, recorded around 15mm of rain from this event. This panoramic photo was taken from the Upper Barracks in Valletta. Towards the right, one can notice the buffeting of the rain-free cloud base due to cool downdraught winds, the ragged edges being the supplementary feature, arcus. The first thumbnail is a single photo shot of the heavy rain shower falling underneath the cloud indicating its very small coverage when comparing it against building structures on the background. The second thumbnail is another dramatic local cloud photo showing a wall cloud or cumulonimbus murus which is defined as an abrupt lowering of the cloud from the base situated in the rain-free zone. This indicated strong updraughts to the localized storm and resulted in the formation of a funnel cloud to its west which never materialized into a tornado or waterspout. The third thumbnail is the weather sounding showing that the locally developed storm clouds had fully maximized all the provided storm ingredients such as available instability. The cloud formations were triggered by convectional heating of land by the still strong Autumnal sun under very light winds as shown in the sixth thumbnail. The storm despite being localized could have been multi-cellular and indeed small hail was reported in areas but wind shear was lacking. The visible satellite imagery on the fourth thumbnail show a close-up view of the storm clouds around the Maltese Islands whilst the fifth thumbnail is the corresponding Luqa rainfall radar image showing heavy rain just over the SE of Malta as described. The surface pressure chart on the seventh thumbnail indicated a weak high pressure system close to the Maltese Islands.

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