Roll and Shelf Clouds Sweep São Paulo Coast as Gust Front Advances Toward Rio

Overview

• Dramatic low clouds over Ilhabela and Bertioga drew wide sharing on social media after forming Saturday along the São Paulo coast.
• State civil defense identified the event as a gust front linked to a passing storm and the arrival of a cold front over the ocean.
• The agency measured 50–60 km/h wind gusts with a shift in wind direction as the system advanced toward the latitude of Rio de Janeiro.
• Reports documented both a roll cloud, a horizontal tube-shaped formation known as volutus, and a shelf cloud, a dense wedge on a storm’s leading edge.
• Meteorologists said colder air racing along the surface forced warm, moist air upward, producing rapid condensation that often precedes heavy rain and a temperature drop.