Extratropical cyclone generates winds of up to 150 km/h in Patagonia and storm surge in southern Brazil

An extratropical cyclone intensifies in the South Atlantic and is expected to reach destructive force between this Monday (17) and Tuesday (18), mainly in Argentine Patagonia and close to the Malvinas Islands. Argentina’s National Meteorological Service predicts gusts that could exceed 150 km/h in open areas in the south of the continent. In Brazil, the effects are restricted to Rio Grande do Sul, with moderate winds and the possibility of a hangover on the coast.

The formation of the system occurs from an area of low pressure that quickly deepens into the ocean. The phenomenon follows the typical trajectory of extratropical cyclones in the southern hemisphere during spring.

• More intense gusts are concentrated on the Patagonian coast
• Central pressure may fall below 980 hPa
• Strong wind also affects sectors of Uruguay and the extreme south of Rio Grande do Sul

Expected trajectory for the next few days

The cyclone is expected to move east-southeast over the next 48 hours. On Tuesday, the center of the system passes close to the east of the Falkland Islands. From Wednesday onwards, the wind field gradually weakens over the continent.

Numerical models indicate that the most intense part remains away from the Brazilian coast. MetSul Meteorologia highlights that Rio Grande do Sul is just on the edge of the system.

Expected effects in Rio Grande do Sul

The most significant gusts in the state occur betweenTuesday night (18) and Wednesday morning (19). On the southern coast of Rio Grande do Sul, winds can reach 50 to 60 km/h. In Porto Alegre, the predicted maximum speed is around 40 km/h in the south of the capital.

The Brazilian Navy issued a storm surge warning for the coast between Rio Grande do Sul and Santa Catarina. Waves can reach 3.0 meters at sea between Wednesday and Friday. No significant coastal flooding is expected.

Severe weather warning in other regions

The National Institute of Meteorology maintains red alert for large areas of the South, Central-West and Southeast until this Monday. The forecast includes heavy rain and gusts above 100 km/h in Santa Catarina, Paraná and Mato Grosso do Sul.

Areas of western Santa Catarina and southwest Paraná are at greater risk of isolated storms. Phenomena such as downbursts and microexplosions are not ruled out at specific points.

Sea conditions later in the week

Sea agitation persists even after the cyclone has passed. Ships and small vessels should avoid sailing on the high seas in the south of the country. Beaches on the coast of Rio Grande do Sul can record waves of up to 2.5 meters until Friday (21).

The Civil Defense of Rio Grande do Sul advises the population to secure loose objects in external areas. No prolonged power outages or widespread damage are expected in the state.

Forecast for the next seven days

Fromr the weekend, a mass of cold air of polar origin advances through the South. Temperatures drop significantly in Rio Grande do Sul, Santa Catarina and Paraná. The combination of humidity and cold favors the formation of frost in higher altitude areas of the mountains of Rio Grande do Sul and Santa Catarina next Monday (24).