Flooding in Porto Alegre is far from over; understand what to expect

What MetSul Meteorologia sees in the model maps it analyzes every day is absolutely saddening and heartbreaking for those who, as part of our team of meteorologists and hundreds of thousands of other people, whose houses are still under water in the flood.

The Guaíba flood is far from over in Porto Alegre. Although the Guaíba fell this Wednesday to close to 5.00 meters after four days of stability between 5.25 m and 5.35 m, rain and wind will prolong the flood with new moments of rising levels.

This Thursday, for example, a southerly wind in the northern sector of Lagoa dos Patos will be associated with the entry of a mass of colder air, generating damming, causing a temporary rise or reducing the rate of water fall.

The problem is that it comes later. Once this Thursday’s south wind is overcome, Guaíba tends to have a downward trajectory with lower flow arriving from the rivers that flow into Porto Alegre. But this falling flow will not last.

The rain expected in the tributaries between Friday and Monday will be excessive, with volumes equivalent to one or two months of precipitation in just four days, bringing a lot of water to the Guaíba next week, which signals a new rise in water levels.

If that wasn’t enough, the rain will sometimes be heavy in the capital, worsening flooding due to the compromise of macro-drainage. The rainwater network, saturated with water from the Guaíba, will be unable to absorb the large volume of rainwater in part of the city.

Another complication will be the wind. When a cold air mass of polar origin arrives next week, from Tuesday to Wednesday, there will be a strong south wind with a new high in Guaíba. When the south wind blows strong, Guaíba can rise 20 cm to 50 cm, depending on the strength of the wind, in a few hours.

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