The geographic scope of the alert covers western and southwestern Paraná, western Santa Catarina, and several regions of Rio Grande do Sul, including the Serra region. INMET emphasizes that while the warning covers broad areas, severe thunderstorms often produce highly localised damage; powerful winds and intense rainfall may affect individual municipalities while neighbouring areas experience less significant conditions. Residents and travellers are advised to seek shelter and avoid exposed outdoor locations, with particular caution urged for those planning long-distance journeys through rural or mountainous areas where access roads may be obstructed by debris or flooding.
This weather event occurs in a region with a recent and painful history of extreme hydro-meteorological disasters. The current alert follows just three days after a tornado damaged Chapecó Airport in Santa Catarina on November 4, where winds reached 126 kilometres per hour, forcing the suspension of flights. However, the most significant context for the current storm is the massive flooding that struck Rio Grande do Sul in April and May 2024. During that period, between 24 April and 4 May, over 420 millimetres of rain fell in the state, leading to floods that affected more than 90% of the region. The disaster displaced over 80,000 people, resulted in more than 150,000 injuries, and caused 169 fatalities by May 29, with 44 people still missing at the time of reporting. Essential services were severely disrupted, leaving 418,200 households without electricity and over a million consumer units without water.
Scientific analysis has sought to understand the drivers behind the 2024 catastrophe. A collaborative study involving researchers from Brazil, the United Kingdom, Sweden, the Netherlands, and the US examined whether human-induced climate change altered the likelihood and intensity of the rainfall. The study analyzed 4-day and 10-day rainfall accumulations to capture both the peak severe event and the succession of heavy rainfall. Southern Brazil, characterized by a subtropical climate with continuous moisture supply from the Atlantic and Amazon, sees rainfall variability influenced by large-scale phenomena such as the El Niño Southern Oscillation (ENSO). The research aimed to quantify the role of both global warming and ENSO in exacerbating the extreme precipitation that led to the 2024 floods.
Two years after the 2024 disaster, recovery efforts in cities like Porto Alegre face critical challenges. In Porto Alegre, the state capital, poor areas are still recovering, and residents express fear that official neglect has left them exposed to new weather events. While federal housing programs such as the “Assisted Purchase” initiative have provided 200,000 reais towards new properties, with 5,800 of 9,477 applicants approved in Porto Alegre, the implementation has been controversial. The program involves the demolition of old homes, leaving some residents in rubble in neighborhoods like Ilha Grande dos Marinheiros and Sarandi. Critics, including local advocates, argue that the program negotiates assistance on a family-by-family basis rather than at the community level, potentially promoting dispersal and gentrification. More than 50% of Assisted Purchase recipients in the city bought homes in other municipalities, further fragmenting local social networks.
The distinction between individual weather events and long-term climate trends is crucial in understanding the current situation. While the November 7 storm is a specific meteorological forecast, it occurs against a backdrop of increasing frequency and intensity of extreme weather events in the region. Previous events, such as the extratropical cyclone in June 2023 that killed more than a dozen people and caused widespread flooding in Rio Grande do Sul, highlight the persistent vulnerability of the region. That 2023 storm, which brought 300 millimetres of rain in 24 hours to areas like Maquiné, was part of a series of major flooding events that year, including landslides in São Paulo in March and wind and hail damage in Porto Alegre in April.
As the red-level warning takes effect, the focus remains on immediate safety and infrastructure resilience. The potential for disruption to road transport and utility services underscores the need for accurate forecasting and rapid response mechanisms. For communities still grappling with the aftermath of the 2024 floods, the current storm represents not just a weather event, but a test of the adequacy of recovery measures and the durability of social and physical infrastructure in a changing climate.
