Heatwave hits 2,700 Brazilian cities, should end Friday

The phenomenon is mainly affecting the Southeast and Central-West

Published on 16/11/2023 - 11:44 By Léo Rodrigues - Rio de Janeiro

The heatwave that is mainly affecting Brazil’s Southeast and Center-West regions is expected to last until Friday (Nov. 17). The forecast was made by the National Meteorological Institute (Inmet), which lists 2,707 affected municipalities.

According to the institute’s classification, heat waves occur when the temperature remains 5ºC above the average expected for the month for at least five days. The 40ºC mark has been exceeded in recent days in Rio de Janeiro and Cuiabá, plus a large number of non-capitals.

States facing the heatwave should receive heavy rainfall next week. In the Southeast, the drop in temperature on Friday (17) is likely to be accompanied by precipitation.

For November 21–29, some locations should receive a large volume of rain, upwards of 40 millimeters, especially in the states of Mato Grosso, Goiás, Minas Gerais, Rio de Janeiro, and Espírito Santo, in addition to the Federal District. In other areas, the authority does not rule out the possibility of showers.

El Niño

The heatwave sweeping across much of the country is strongly associated with the El Niño phenomenon, researchers believe. It is characterized by the weakening of the trade winds (which blow from east to west) and the abnormal warming of the surface waters of the eastern portion of the equatorial Pacific Ocean. Changes in the interaction between the ocean surface and the lower atmosphere have consequences for weather and climate in different areas of the planet. This occurs because the circulation dynamics of air masses take on new patterns of moisture transport, affecting temperature and the distribution of rainfall.

Geographer Marcos Freitas, a researcher at the Federal University of Rio de Janeiro (UFRJ), draws attention to measurements carried out by the National Oceanic and Atmospheric Administration, linked to the US government. The agency, he pointed out, gauges the temperature of the water in the so-called Zone 3.4, located in the central equatorial portion of the Pacific Ocean.

“We’re getting close to a 2ºC anomaly. Usually, we have a medium or weak El Niño every two years, which is when we see an anomaly of 1ºC at the most. When it rises above 1ºC, we call it a strong El Niño. This alters the air masses over our continent.”

“We’re facing a strong El Niño,” he argued, which is blocking the entry of masses of humidity in part of the Southeast and a little in the Center-West.

The trend also points to a sweltering summer, he went on to say. “This El Niño is not going to dissipate now,” he added.

The World Meteorological Organization estimates that the effects of the phenomenon should be felt until at least April next year. Marcos Freitas noted that a strong El Niño occurs more or less every seven years, but its intensity has been on the rise as a result of global warming.

Translation: Fabrício Ferreira -  Edition: Nádia Franco

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