Understand why it's raining so much in Rio Grande do Sul

Rio Grande do Sul is facing an unusual situation of storms and intense rain, as explained by the climate and environment analyst at CNN , Pedro Cortês. The state is being “attacked” by cold fronts coming from the south of the continent, but which are unable to progress due to a high pressure zone in the center of Brazil, functioning as a “wall”.

This same high pressure zone diverts moisture from the Atlantic Ocean to Rio Grande do Sul from the east and the Amazon, entering from the west. Thus, the state receives moisture from all directions, while the current cold front cannot escape.

“It’s what I would call a perfect storm, because Rio Grande do Sul is being affected by cold fronts coming from the south of the continent, but these fronts are unable to progress due to a high pressure zone in the center of Brazil”, said Cortes.

Simulations and predictions

The expert presented simulations of the European weather forecast model, showing the expected rainfall accumulated from the day before until next Friday (12). The images indicate large volumes concentrated in Rio Grande do Sul, with red and purple areas indicating the intensity of precipitation.

Meanwhile, the central region of the country remains without rain throughout the week, with high temperatures of more than 30 °C in the Central West. According to Cortês, this mass of hot and dry air should continue at least until mid-May.

Deaths in RS

A balance released by the government of Rio Grande do Sul in the early evening of this Friday (12) shows that the number of deaths due to the heavy rains that hit the state since the beginning of the week rose to 39. In total, 265 municipalities were affected, more than half of the state of Rio Grande do Sul.

In addition to the deaths, the state reports 74 injured, and another 68 missing. In total, 351,639 people were affected by the storms in Rio Grande do Sul, with 24,080 homeless and 8,168 in shelters.

See where the deaths occurred:

• Cinnamon (2)
• Candelaria (1)
• Caxias do Sul (1)
• Bento Gonçalves (1)
• Boa Vista do Sul (2)
• Paverama (2)
• Pantano Grande (1)
• Pinhal Grande (1)
• Putinga (1)
• Lawn (4)
• Itaara (1)
• Enchanted (1)
• Salvador do Sul (2)
• Serafina Corrêa (2)
• Secret (1)
• Santa Maria (2)
• Santa Cruz do Sul (4)
• São João do Polêsine (1)
• Silveira Martins (1)
• Vera Cruz (1)
• Taquara (2)
• Saint Wendelin (2)
• Three Crowns (3)

Difficulties in rescues

Relief teams face obstacles in reaching the most affected regions. More than 100 sections of state and federal highways are blocked, making land access difficult. Rescues are being carried out by boat and air, when possible.

Authorities work to guide the population to seek refuge, whether in high places or with relatives and friends. The forecast is that levels will continue to rise in the coming hours, further worsening the situation.

Bridge closures

This Friday (3), the federal government closed the bridges over the Guaíba River, in Porto Alegre, after the volume of water exceeded 4.6 meters above the normal level. Traffic at the site will only be permitted for ambulances and vehicles operating to rescue victims.

Speaking to CNN, the Minister of Transport, Renan Filho, said that the blockage was made due to water pressure on the pillars that support the bridge. Furthermore, vehicle traffic could further increase the pressure on the structure.

“We believe that the pillars will sustain the pressure, but it is a safety measure, as the water level is close to the 1941 record,” said the minister.

Dam failure

The Bugres dam, in the city of Canela, in Serra Gaúcha, is at risk of imminent failure, requiring measures to preserve lives, according to a bulletin released by the government of Rio Grande do Sul.

The 14 de Julho dam, in Cotiporã and Bento Gonçalves, is also at Emergency level, with imminent risk of failure. The dam is monitored by ANEEL and ONS, it collapsed on Thursday afternoon (2) due to the heavy rains that have hit the state since the beginning of the week and the situation remains unchanged until Friday afternoon.

Two other dams monitored by the Secretariat for the Environment and Infrastructure (Sema) are also at risk of imminent failure. They are: Arroio Barracão Dam, in Bento Gonçalves, there was erosion on the right bank of the dam and 50 families are being evacuated, and Saturnino de Brito Dam, in São Martinho da Serra, with the need to evacuate the potentially affected population.