An extratropical cyclone, which will form on the Brazilian coast between the night of this Tuesday (9) and the dawn of Wednesday (10) should cause drops in temperatures, heavy rains and gusts of winds of up to 100 km/h in the states in the South and Southeast of the country.
Due to the change in weather conditions, the National Institute of Meteorology (Inmet) issued warnings of great danger for different regions of Rio Grande do Sul, Santa Catarina, Paraná and also for the cities of the coast of São Paulo.
The forecast is that the cyclone will form on the coast of Paraná and Santa Catarina and São Paulo and cause gusts of wind and rain in the three states throughout Wednesday, especially in coastal cities.
Minas Gerais and Rio de Janeiro are also expected to receive rain showers during the day, but they are off Inmet’s alert radar.
Due to the formation of the cyclone, Inmet issued warnings of danger due to heavy rains and high-intensity coastal winds.
The heavy rainfall alert was directed to: Vale do Itajaí, Grande Florianópolis, Metropolitan Region of Curitiba, north and south of Santa Catarina, Metropolitan Region of Porto Alegre, Serrana, and northeast of Rio Grande do Sul. The forecast for these regions is for rain greater than 60 mm/h or greater than 100 mm/day, with winds greater than 100 km/h.
Due to the weather conditions, the institute reports that there are great risks of “damage to buildings, power cuts, falling trees, electrical discharges, flooding, flash floods and major disruptions to road transport.”
The recommendations in the face of these conditions are: turn off electrical appliances and the general energy board; put documents and valuables in plastic bags in case of floods; and avoid staying outdoors if a dangerous situation is confirmed.
Regarding coastal winds, the alert is intended for the metropolitan regions of Curitiba, Paraná; south coast of São Paulo and also to Grande Florianópolis, north and south of Santa Catarina, metropolitan region of Porto Alegre, Vale do Itajaí, Serrana, and northeast of Rio Grande do Sul.
extratropical cyclone
The extratropical cyclone is the result of a confluence of winds towards a center of low atmospheric pressure, which is associated with rainfall and instability – atmospheric pressure is one of the factors that determine weather conditions.
The phenomenon is common in Brazil and tends to travel along the coast generating rain, winds, high waves and hangovers. Its formation, unlike tropical cyclones (which are hurricanes), takes place further away from the tropics – hence the name “extratropical”.
At the rear of the cyclone there is a center of high atmospheric pressure which, in turn, is related to stable weather. Ana Ávila, a researcher at the Center for Meteorological and Climate Research Applied to Agriculture (Cepagri) at the University of Campinas (Unicamp) explains that when there is an imbalance between points of lower and higher atmospheric pressure, gusts of wind occur.
“If there is a point with lower atmospheric pressure and another with higher atmospheric pressure, the wind tends to equalize this difference. So, this extratropical cyclone will generate strong winds, up to 100 km/h, because of this situation”, says the researcher.
The circulation of winds prior to the formation of the cyclone has already caused, this Tuesday, a drop in temperature and rainfall in the states of Mato Grosso and Mato Grosso do Sul, after a long period of drought in the region. Those who live in the capital of São Paulo have also been able to perceive the effects of instability with the drop in temperatures with heavier clouds in the sky.
As the cyclone moves away, the rains and winds lose intensity and give way to the cold, which should be felt from Thursday, 11. “The sharp decline in temperatures is due to an air mass of origin that will accompany the cyclone and that will invade the entire south-central region of the country”, explains Ana.
In the South, the Inmet forecast indicates a small chance of snowfall in the Santa Catarina mountain range and frost formation between Thursday and Friday (12) in Serra Gaúcha and in the Catarinense and Paraná Plateaus. In the south of Mato Grosso and in the northeast of São Paulo, according to the institute, there is also a remote possibility of frost.
Source: CNN Brasil
