Cb calvus

A line of cumulonimbus clouds forming the squall line thunderstorms that crossed the Maltese Islands at late afternoon. This was associated with a cold front coming from Africa in relation with a mid-latitude cyclone. Both this cloud and the first thumbnail photo could be associated with the cold sector of the mid-latitude cyclone graphics as depicted in the following charts being the thunderstorm satellite image on the third thumbnail integrated with the SLP chart on the sixth thumbnail and the rain radar image on the fifth thumbnail. The cold front moving in from the SW led to an abrupt change in wind from a pre-frontal very strong ENE wind to a light SW wind along with a slightly cooler temperature as depicted in the surface wind field of the fourth thumbnail. The photographed cumulonimbus is of the calvus species because the upper parts were flattened and was a brownish mass (due to sunset) without any sharp outlines or fibrous and striated anvils. Lightning was noticed flashing from time to time within the cloud band and typical of such cloud it produced an unofficial rain rate of 340mm/hr though the storm was rather short-lived. The first thumbnail showed part of the cumulonimbus that reached a stable layer of the atmosphere hence transitioning to capillatus incus with clear mammatus features as the air started to descend. The second thumbnail is altocumulus stratiformis undulatus immediately following the passage of the storm with the departing heavy rain band still visible in the background and cumulus clouds seemingly touching the higher ground on the background western side of Malta. Such a squall line is rather a rare event for Spring in Malta as it’s more associated with late Summer or Autumn when there is lots of instability involved. It was also covered in the news vide this article: https://www.timesofmalta.com/articles/view/20190321/local/cars-flooded-in-mriehel-yet-again.705148

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