EN 
PT_BR 
The risk of isolated tornadoes puts areas of southern Brazil and Mato Grosso do Sul on alert this Thursday (10) and, especially, on Friday (11). According to the National Institute of Meteorology (Inmet), the combination of strong instability, humidity and intense winds may favor the formation of severe storms and, in some places, phenomena such as tornadoes and microbursts.
Paraná, Santa Catarina, Rio Grande do Sul, and Mato Grosso do Sul are among the areas requiring the most attention. However, Inmet (National Institute of Meteorology) emphasizes that it is not possible to determine in advance where a tornado will occur. The forecast only indicates that atmospheric conditions will be favorable for storms capable of producing these phenomena in localized areas.
For Thursday (10), Inmet has issued a red alert for high-danger storms in areas of southern Mato Grosso do Sul, Paraná, Santa Catarina and the extreme northwest of Rio Grande do Sul. The forecast includes heavy rain, thunderstorms, hail and intense gusts.
On Friday, instability increases over the Southern Region. The institute points to the possibility of instability lines and supercells, as well as strong downdrafts, which could cause very intense gusts and, in some areas, tornadoes.
Why is there a risk of a tornado?
The risk is related to the highly unstable environment that forms with the interaction of low-pressure areas, high humidity, and strong winds. Under certain conditions, some storms can become organized enough to produce severe phenomena.
This does not mean that there will be tornadoes throughout the entire warning area. The possibility is localized and depends on the evolution of each storm.
Extratropical cyclone forms over the ocean on Friday.
The unstable scenario is also linked to the formation of an extratropical cyclone, but it is important to note that the system will not be formed over the continent.
According to meteorologist Andréia Ramos, the low pressure system will begin moving towards the Atlantic Ocean on Friday, and the cyclone should be formed over the ocean by around 3 PM.
"Throughout Friday, we will begin to observe this low pressure system moving towards the Atlantic Ocean, and around 3 pm, more or less in the middle of the afternoon on Friday, we will already have this extratropical cyclone forming over the ocean."
Even though it forms over the Atlantic, the system's organizing process helps maintain a fairly unstable atmosphere over areas in the South and South-Central regions of the country.
"Although the cyclone forms over the ocean, the process of formation and organization of this cyclone favors the formation of these rain showers, which can come in the form of storms, with hail and also with gusts of wind."
Paraná, Santa Catarina, and Mato Grosso do Sul require attention.
Between Thursday and Friday, Paraná, Santa Catarina, and Mato Grosso do Sul are among the areas of greatest concern for severe storms.
In Paraná and Santa Catarina, the forecast indicates favorable conditions for more intense storms. In Mato Grosso do Sul, instability will also intensify throughout Friday, especially in the southern half of the state.
Andréia draws attention to the advance of the storms during the night:
"Towards the end of the night, the likelihood of storms increases over Mato Grosso do Sul. Especially in areas of the southern half of the state, there is a chance of more intense rainfall."
Inmet also points out that, between Thursday and Friday, the area between Mato Grosso do Sul, Paraná and Santa Catarina has one of the highest potential potentials for severe weather.
São Paulo will also experience heavy rain and storms.
Although São Paulo is not among the main areas indicated by Inmet (National Institute of Meteorology) for tornado occurrence, the state is also entering a period of instability, mainly starting on Friday.
The forecast indicates rain and thunderstorms in different areas of the state, with particular attention to the extreme south of São Paulo, which is under an orange warning for dangerous storms.
Andréia explains that the rain should move more significantly over São Paulo starting in the late afternoon:
"In São Paulo, the areas in the southern half of the state as well. Starting late Friday afternoon, the potential for more significant rainfall increases."
The early morning hours from Friday to Saturday also deserve attention due to the possibility of storms, hail, and stronger winds.
"And we highlight, then, the early morning hours from Friday to Saturday, where there is the greatest potential for hail, with stronger winds also advancing over Mato Grosso do Sul and areas of the state of São Paulo."
