Rain lasting half a month in hours floods cities in Greater Porto Alegre

The intense rain in the late afternoon and early evening caused flooding in several cities in Greater Porto Alegre during the arrival of the cold front. Accumulations in different parts of the metropolitan region of the capital of Rio Grande do Sul reached half the historical average for the entire month in just a few hours.

The rain had already started in the middle of the afternoon with some heavy showers after hours of overcast and very muggy weather in the region. The maximum temperature at the National Institute of Meteorology station in Campo Bom, in Vale do Sinos, reached 30.7ºC in the early afternoon. Porto Alegre reached 28ºC.

Due to the instability in the middle of the afternoon with very heavy clouds and turbulence that made the approach difficult, several aircraft were in orbit waiting to land in Porto Alegre and an Azul flight even made a go-around, a normal procedure in aviation. The rain in the late afternoon, however, came more heavily.

The accumulated rainfall in just six hours, between 3 pm and 9 pm, in the National Disaster Monitoring Center network, reached 64 mm in Sapucaia do Sul, 61 mm in Canoas, 59 mm in Novo Hamburgo, 58 mm in Gravataí, 46 mm in Eldorado do Sul, 45 mm in Viamão and 43 mm in Porto Alegre and Alvorada.

To give you an idea of ​​how high these volumes are in such a short period, the historical average rainfall in Porto Alegre in the month of April is 114.4 mm, according to the 1991-2020 climatology of the Jardim Botânico neighborhood station. It means that Greater Porto Alegre in just six hours had rain equivalent to almost half or even above half of the average rainfall for the entire month in just a few hours.

City halls in the metropolitan area such as Canoas, Porto Alegre and Novo Hamburgo reported points with accumulation of water and flooding on public roads. Where the disruptions were greatest due to the excess rain caused by the cold front was in Vale do Sinos.

Several streets in Novo Hamburgo were flooded in the early evening of this Saturday and there were points where cars were unable to pass, such was the amount of water in sight. The stream on Avenida Pedro Adams Filho overflowed with the intense rain, worsening flooding nearby.

MetSul meteorologist Luiz Fernando Nachtigall explains that the worst is over. The weather remains unstable and a period of heavier rain cannot yet be ruled out, but the tendency is for the precipitation to remain predominantly light until it stops during this Sunday, a day that will be full of clouds and occasional openings with milder temperatures.

The bad news is that there is a lot of rain to come in the next few days. MetSul insists that Rio Grande do Sul will be between colder air to the South and a powerful mass of hot air over Brazil throughout next week. Depending on the day, sometimes warmer air advances from the North to the state, sometimes colder air will move from the South to the Rio Grande do Sul territory with warm fronts and cold fronts.

Since it will be in the transition zone between the two air masses, hot and cold, instability will be frequent with the expectation of a lot of rain. The accumulated rainfall throughout the week in the state will be excessively high and will add to the voluminous rain that has already fallen, so that once again we reiterate that the risk is high that rivers and floods will occur in the state at the beginning of May. .

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