Porto Alegre is experiencing the wettest month since 1916

September 2023 is the wettest month in Porto Alegre in the last 107 years. Until the early morning of the 26th, the amount of rain was almost triple the average.

According to calculations by the National Institute of Meteorology, Porto Alegre is having the wettest month in the last 107 years, since regular measurements began in 1916.

In the period from 1 to 26 September 2023 Porto Alegre accumulated 413.8mm of rain, almost triple the normal average rainfall for the month of Septemberwhich is approximately 148mm.

September 2023 is now the wettest month ever observed in the history of Porto Alegre’s climate, documented by the National Institute of Meteorology since 1916.

The rainfall of September 2023 exceeded that of May 1941, until then the month with the greatest amount of accumulated precipitation.

Photo by André C., Porto Alegre (RS)

The rainiest months in Porto Alegre

Consult the ranking of the wettest months in Porto Alegre, based on measurements by the National Institute of Meteorology of the Jardim Botânico meteorological station, from 1916 until 9:00 on September 26, 2023.

Rainiest months in Porto Alegre from 1916 to September 2023 (Photo: Getty Images)

More rain is forecast for this Wednesday. Thursday will be sunny and it will rain again on Friday and Saturday. On Sunday 1 October the weather will be sunny.

More than 600 mm within Rio Grande do Sul in September 2023

The entire state of Rio Grande do Sul is experiencing a September with extremely high rainfall volumes, well above the normal average, which does not exceed 220 mm. In some areas, it rained from 500 mm to 620 mm in 30 days, between 26 August and 26 September 2023.

The map shows that in Rio Grande do Sul it has rained from 300 to almost 500 mm, and for most of the state the average rainfall for September varies from 140 mm to 180 mm.

Accumulated rain in RS in 30 days, between 8/26/23 and 9/26/23 (Source: Inmet)

Look at how much rain it has rained in some places

Caçapava do Sul: 620.4 mm

Ibirubá: 500.0 mm

Capacity: 482.6mm

Southern Cross: 470.8 mm

San Gabriel: 468.6 mm

8 extratropical cyclones near RS from 06/15/23 to 09/15/23

The influence of El Niño began to be felt in June 2023, when the phenomenon began to take shape. Since then, El Niño has gained strength and is now considered a strong event.

In 16 weeks, between 15 June and 15 September 2023, 8 extratropical cyclones formed near Rio Grande do Sul, practically 1 every 2 weeks. Although only one of them actually formed over the state, the process of forming all of them contributed to the formation of large, persistent, strong areas of instability that caused heavy rainfall over the entire Rio Grande do Sul.

8 extratropical cyclones form near the RS between June 15 and September 15, 2023 (Art: Climatempo)

It is important to remember that Rio Grande do Sul had a maximum of 2 days of respite between one episode of heavy rain and another. In several situations, many areas of the state experienced heavy rainfall on already flooded, soggy areas with no conditions for drainage or soil absorption of the water. The rain fell heavily on the rivers and streams already full of water.

A new cold front and another extratropical cyclone will form on Wednesday, September 27. The cyclone forms over the sea and moves rapidly away from the southern region.

Two sunny days for the gauchos

The rain will give RS a break on Thursday and Friday and it will also be cold at night and at dawn; The sun predominates these days, but temporary rain may occur on the plateau on Thursday afternoon. Friday will be sunny, but with a chance of rain showers in the west, missions, northwest, plateau and mountains (north and west of RS) Showers will return to most of the state on Saturday, but it will be sunny again on Sunday.

Why so many cyclones?

The El Niño phenomenon, an anomalous warming of sea water in the equatorial Pacific Ocean off the coast of Peru, has increased the frequency and intensity of warm, moist air currents from north to south Brazil. This more frequent “injection” of warm, moist air, unlike the cold air passing over Argentina and Uruguay, facilitates the formation of extratropical cyclones. These weather systems form from large temperature differences.

El Niño intensifies the warm air current over the south, which increases the thermal contrast and creates the conditions for the formation of extratropical cyclones.

Spring with more rain

OR El Niño gains even more strength in spring and more cyclones, or other low air pressure systems, could form, causing more rain over Rio Grande do Sul.

It is necessary to remember that the Spring is a season of heavy rain in the south, even without El Niño. This phenomenon will continue to strengthen until the end of the year. The most recent analyzes from the main global climate monitoring centers indicate a weakening of El Niño only in the autumn of 2024.

Climatempo predicts that the Rio Grande do Sul will still have a lot of rain throughout the spring. Precipitation is expected to be above the historical average during October, November and December.

Given the large volume of water already falling on the state, additional flood events, inundations and complications caused by excessive rainfall should be expected.

Source: Terra

Rose

Rose James is a Gossipify movie and series reviewer known for her in-depth analysis and unique perspective on the latest releases. With a background in film studies, she provides engaging and informative reviews, and keeps readers up to date with industry trends and emerging talents.