What is an extratropical cyclone that hits part of Brazil – 06/16/2023 – Environment

An extratropical cyclone, meteorological phenomenon responsible for causing heavy rains and winds, acts this week in part of Brazil, with the effects felt on the coast of the South and Southeast region until Friday (16), bringing heavy rains and gusts of wind in cities from Rio Grande do Sul, Paraná, Santa Catarina and São Paulo.

The strongest effects should be felt in places further south in the country: the Inmet (National Institute of Meteorology) warns of high rainfall —above 60 millimeters per day or greater than 100 millimeters per day) with winds greater than 100 km /h in Santa Catarina and Rio Grande do Sul.

Common in Brazilian climatic history, extratropical cyclones tend to form in the extreme south of the country, between Rio Grande do Sul and Argentina and Uruguay, neighboring countries. Its winds are weaker and its effects have a shorter duration compared to tropical cyclones.

“Extratropical cyclones in the Atlantic Ocean form every week, dozens of them at times. But it’s common for them to form near the south pole, very far away. That’s why we don’t mention it in the weather forecast — an extratropical cyclone a thousand kilometers from the coast is not going to cause no effect on the population”, explains Estael Sias, meteorologist at MetSul, a meteorological content platform.

The difference between the phenomenon we are seeing now is that, as happened last year, its formation area is closer to the Atlantic coast, making the population feel the effects.

“The formation is not as fast as that of a tornado, for example, which happens in minutes”, points out Ana Avila, meteorologist and researcher at Unicamp (State University of Campinas).

There is a risk of flooding, landslides and flash floods, as well as roofing, damage to electrical networks and falling trees and branches.

The risks vary according to the region and the intensity with which the cyclone must act. That’s why it’s important to always be alert to the recommendations of the Civil Defense and other competent bodies in your city and state.

An example is the difference in the strength of wind gusts between Florianópolis and the city of São Paulo. Further south, the wind is forecast to reach 100 km/h. In São Paulo, the biggest gusts should oscillate between 60 km/h and 80 km/h.

The CGE-SP (São Paulo Emergency Management Center) recommends that anyone in the city of São Paulo not stay under the power grid or trees and avoid displacements.

In cities in the south of the country, with a higher risk of flooding, the recommendations of the competent bodies range from seeking safe shelter to not coming into contact with water.

Coastal cities should also feel greater impacts. “The winds are stronger near the sea, as well as the waves, which can reach four meters in height. Therefore, it is essential that all maritime activities, such as fishing, be canceled. The risk is very high, as the alerts meteorological data from civil defenses have been pointing mainly in the last 24 hours”, explains Avila.

Extratropical cyclones are centers of low atmospheric pressure that form outside the tropics, at mid- and high-latitudes.

“It is formed by the contrast of warm and cold air masses. Part of its action is to suck all the moisture into this region of the low pressure center and throw it into the atmosphere, cooling and transforming the moisture into clouds. It is in this process that the phenomenon spreads rain and wind”, points out meteorologist Estael Sias.

How people should protect themselves

In more affected areas, the recommendations call for greater caution. Below, as an example, are the advice of the Civil Defense of Santa Catarina:

flooding

Avoid contact with water
Do not drive in flooded areas
Avoid underwater bridges and footbridges
Pay attention to the children

landslides

Stay tuned:

To slanting poles and trees
Any earth movement or slopes near your residence
Appearance of cracks in walls or walls

Strong winds

Find a sheltered location, away from trees, signs, poles and other objects that can be thrown
In sheltered location, stay away from windows.