A group of storm chasers recorded a supercell in the Alegrete region, on the Western Border of Rio Grande do Sul, this Saturday afternoon (26). The formation was filmed at around 6:50 pm, during a sequence of storms passing through the state.
So-called storm chasers are researchers passionate about meteorology and atmospheric phenomena who follow severe weather events to record and study these formations.
Among the group's members was North American Nader Mike, who came to Brazil to monitor severe meteorological phenomena. Alongside Rio Grande do Sul photographer Gabriel Zaparolli, he broadcast live monitoring of the storm.
In a post on social media, Zaparolli classified the formation as a "monstrous supercell" and stated that a possible tornado could have formed briefly in the region.
The occurrence, however, still needs to be confirmed by meteorological analysis.
What is a supercell?
A supercell is a type of severe storm characterized by the presence of an ascending air current that rotates within the cloud. This rotation, known as a mesocyclone, means that the storm can remain organized and active for longer than a common storm.
This type of formation can cause extreme phenomena, such as large hail, very strong winds and, in certain conditions, tornadoes.
For a supercell to develop, the atmosphere needs to bring together a combination of factors. These include high availability of moisture, heat, atmospheric instability and significant changes in wind speed and direction as altitude increases.
These differences between winds from near-surface layers and those higher up in the atmosphere help produce rotation within the storm.
Therefore, a supercell does not necessarily mean there will be a tornado. Although some of these storms can generate tornadoes, their occurrence depends on an even more specific configuration of the atmosphere.
Storm caused damage in Alegrete
The formation was recorded during a sequence of storms that hit Rio Grande do Sul this weekend.
The state Civil Defense had issued a warning for storms with the possibility of large hail and wind gusts exceeding 80 km/h on Saturday afternoon and evening. For this Sunday (27), the forecast indicated an even greater risk, with winds that could exceed 90 km/h.
In Alegrete, the storm caused hail and damage to properties, especially in the Passo Novo region. Local reports pointed to roofless houses, flooding and problems with the electricity supply.
The state Civil Defense had also placed the Alegrete region on alert for storms with wind and hail, with a high risk of roofing.
Why is RS having so many storms?
The instability is part of a severe weather scenario predicted for the state throughout the weekend. According to Civil Defense, this Sunday the risk of storms increases in areas of Campanha, West, Missions, Northwest, Center, Serra, Northeast and North.
On Monday (28), the forecast maintains the possibility of severe storms and intense rain.
Accumulations between Saturday and Tuesday can vary from 100 to 200 millimeters, with the possibility of exceeding 250 millimeters occasionally in the Campanha, Center and West regions.
The National Institute of Meteorology (Inmet) also identified Rio Grande do Sul as one of the areas of the country with the highest concentration of rain between the 21st and 28th of September, with accumulations exceeding 100 millimeters predicted mainly in the central and western regions of the state.
In addition to intense rain, Civil Defense warns of the possibility of hail, strong winds, flooding and rising river levels.
Among the monitored watercourses is Ibirapuitã, in Alegrete, which may exceed the flood level due to the forecast rains.
The scenario also favors the formation of organized storms, such as the supercell recorded by storm chasers in Alegrete.
