Overview

• A Volutus roll cloud formed off Portugal’s northern and central west coast between Peniche and Póvoa de Varzim on June 29, rolling ashore around 17:00–18:00 UTC.
• Viral videos show beachgoers fleeing in panic as the horizontal tubular cloud resembled a tsunami, packing up and leaving the sand strewn with debris.
• On July 1–2, the Portuguese Institute for Sea and Atmosphere officially confirmed the phenomenon and published satellite imagery, identifying it as a roll cloud added to the WMO International Cloud Atlas in 2017.
• Meteorologists explain that wind shear at gust fronts between warm and cold air masses creates the rolling motion of these clouds and emphasize that they pose no real threat despite their dramatic appearance.
• Roll clouds remain globally rare but are frequently seen as Morning Glory Clouds in Australia’s Gulf of Carpentaria and have been recorded occasionally in New Zealand.