Rainfall could exceed 200 mm in the South-Central region in the coming days.

Above-average rainfall is expected to mark the end of August and the beginning of September in south-central Brazil. According to data released by Meteored, two cold fronts predicted in just seven days could cause severe storms, hail, wind gusts, and even tornadoes, in addition to rainfall exceeding 200 millimeters in areas of the South.

The first system starts to form this Thursday (27) and should remain semi-stationary over the Southern Region until Monday (31). According to data released by Meteored, the ECMWF model indicates unusual to extreme daily rainfall in areas of the region.

The forecast uses the ECMWF Extreme Forecast Index (EFI), which identifies locations where the projected daily accumulation deviates significantly from the normal pattern and may exceed the statistical threshold considered extreme. In some areas, the predicted volumes should exceed 200 millimeters. Between northern Rio Grande do Sul and Santa Catarina, accumulations may approach 300 millimeters by the end of Monday (31).

An intense low-level jet stream, located east of the Andes Mountains, is expected to transport heat and moisture from the Amazon region to southern Brazil. This moisture transport, characterized as an atmospheric river, contributes to increased atmospheric instability and, consequently, the potential for intense storms and heavy rainfall.

According to data released by Meteored, intense storms are expected to form continuously over Rio Grande do Sul, Santa Catarina, and Paraná in the coming days. These storms present a high risk of hail and strong wind gusts, as well as the potential for isolated tornadoes and microbursts. The greatest potential for severity is predicted for Rio Grande do Sul, although other states in the Southern Region may also experience intense storms.

The highest accumulations until the end of Monday (31) should occur between the north of Rio Grande do Sul and Santa Catarina, with volumes above 200 millimeters in several areas. According to data released by Meteored, the accumulation could reach close to 300 millimeters in some places. This scenario increases the potential for disruptions related to flooding. From Monday (31) to Tuesday (1st), the system should advance over the Central-West and Southeast regions.

In these regions, there is also a forecast of storms with heavy rainfall, especially in the Southeast. Although the volumes and intensity are lower than in the South, more urbanized areas remain at risk of disruption.

The second system should begin its formation next Thursday (3). According to data released by Meteored, the ECMWF model indicates that the cold front will have less impact on Rio Grande do Sul and Santa Catarina. Its activity should be concentrated between the north of the Southern Region and Central Brazil, organizing a wide area of convection over the interior of the country. The system also has the potential to cause unusual rainfall for this time of year in the eastern part of the Southeast.

Between Wednesday (2) and Saturday (5), accumulated rainfall could reach 60 to 100 millimeters, with the possibility of disruption. According to data released by Meteored, Rio de Janeiro should be the state most affected by this second system. As the second cold front is still further away on the forecast horizon, the data may undergo adjustments over the next few days. Therefore, according to data released by Meteored, it is important to continue monitoring the evolution of the system and follow the weather forecast updates.