EN 
PT_BR 
Rainfall in the Central-South of Brazil is expected to intensify from Saturday (19), with forecasts of high volumes and new storms in areas that have already faced disruptions in recent days. Rio Grande do Sul, Santa Catarina, Paraná, Mato Grosso do Sul and São Paulo are among the states on alert.
According to data released by Meteored, the change in weather begins with the formation of a trough, an elongated region of low pressure, starting on Friday (18). The system should favor the occurrence of rain and storms during the weekend.
On Friday (18), the rains should concentrate over Paraná and Santa Catarina, with the possibility of isolated storms. The intensity should vary from weak to moderate in these two states. From Saturday (19), however, the conditions change and the rains and storms intensify over a wider area of the Central-South.
According to data released by Meteored, between Saturday (19) and Sunday (20), the daily volume of precipitation will be considered “unusual to extreme” by the extreme forecast index (EFI) of the ECMWF model.
The indicator compares the predicted daily volume with the climatological forecasts of the model itself for a given area. In this way, it highlights regions where precipitation is likely to exceed the statistical threshold considered extreme, corresponding to the 99th quantile.
On Saturday (19), the areas with the highest forecast of intense and heavy rain are between the north of Rio Grande do Sul, Santa Catarina and Paraná. In these locations, the volumes may exceed 60 to 80 millimeters. Also on Saturday, locally intense rains should advance from the northern half of Rio Grande do Sul to the south of Goiás. The instability should also reach Mato Grosso do Sul and São Paulo.
In addition to rain, there is a forecast of intense storms mainly over Paraná, Mato Grosso do Sul and São Paulo. According to data released by Meteored, these areas have the potential for hail. The storms may also extend to Mato Grosso and southern Goiás during Saturday (19).
On Sunday (20), the focus of the heavy rains should change. The most affected areas are between eastern Santa Catarina, northwestern Paraná and, mainly, São Paulo.
According to data released by Meteored, daily rainfall could exceed 50 millimeters in São Paulo and 80 millimeters between Paraná and Santa Catarina. The instability is not expected to end on Sunday. Rain is expected to continue affecting the Central-South region between Sunday (20) and at least Tuesday (22).
During this period, the low pressure is expected to give rise to a cyclone and its associated cold front, maintaining unstable conditions over the region.
Between Tuesday (22) and Wednesday (23), the system should move towards the Southeast and stop affecting the states of the South and Midwest.
According to data released by Meteored, the expected accumulations between Saturday (19) and the end of Tuesday (22) could exceed 150 millimeters in some areas, with the potential to cause further disruption. The most recent run of the ECMWF model indicates that a new band of rainfall above 150 millimeters should establish itself during the episode.
Until the end of Wednesday (23), the areas most affected by the heavy rains should be between the north of Rio Grande do Sul, Santa Catarina, Paraná, São Paulo and part of Mato Grosso do Sul.
In these states, rainfall totals could range from 100 to over 150 millimeters. The highest volumes are initially expected in western Santa Catarina, southwestern Paraná, and southern São Paulo, where they could exceed 150 millimeters.
The situation requires monitoring in the coming days because the weather forecast is still subject to change. According to data released by Meteored, the weather forecast is updated hourly, and both the location and maximum precipitation values may change by the end of the week.
Therefore, monitoring of atmospheric conditions should continue, especially in areas that have already experienced disruptions related to heavy rainfall in recent days.
