Atmospheric microexplosion hit the city of Rio Grande do Sul; see the video

An atmospheric microexplosion hit the Rio Grande do Sul municipality of Santa Cruz do Sul, in Vale do Rio Pardo, during a severe storm on Saturday afternoon. The intense storm was accompanied by heavy rain, destructive gusts of wind and abundant hail.

Santa Cruz do Sul City Hall will declare an emergency situation, reported the Gaz portal of the newspaper Gazeta do Sul. The neighborhoods most affected by the severe wind and hail storm were Linha João Alves and Belvedere, but there were also records in Bonfim and Margarida .

A report by the Civil Defense of Santa Cruz do Sul shows that 3,800 people were affected and at least 750 homes were damaged. Thousands of meters of tarpaulin had to be distributed to residents of the affected areas to cover the roofs of their homes.

Santa Cruz do Sul was the city most affected by Saturday’s storms in Rio Grande do Sul. The Civil Defense of Santa Cruz do Sul had to set up a task force to help people affected by the storm. There were roofs, fallen trees and lack of electricity in Santa Cruz and neighboring cities, such as Vera Cruz.

The highly intense storm that hit Santa Cruz do Sul was caused by the advance of a cold front through Rio Grande do Sul under a mass of very hot air, which formed a storm cell over the Rio Pardo Valley in the early afternoon of Saturday. Further west, in the center of the state, a tornado caused minor damage to rural property in the municipality of São Martinho da Serra.

The meeting of the cold front with the hot air mass favored isolated storms in Rio Grande do Sul, including the formation of supercells. With a strong hot and dry North wind, brought by an intense low-level jet stream, the temperature reached maximums of 33ºC to 35ºC in the Northwest in the afternoon.

Video shows the strength of the storm

Video received by MetSul Meteorologia shows the enormous force of the storm that devastated parts of the municipality of Santa Cruz do Sul in the early afternoon of Saturday. It was a very severe and localized event, which explains the great magnitude of the damage, even in solid constructions.

The recording was made by Augusto Hoffmann, resident of Linha João Alves, one of the areas most impacted by the storm in the city of Vale do Rio Pardo and which concentrated much of the damage observed after the storm passed through Santa Cruz do Sul.

The video shows severe wind conditions that, due to their intensity and duration, and horizontal advance, are typical of a localized and very intense wind phenomenon known technically as an atmospheric microburst or, in English, downburst. MetSul estimates that in the area where the video was recorded, gusts exceeded 120 km/h.

What is an atmospheric microburst

What is a dowburst or atmospheric microburst? This type of phenomenon occurs mainly in summer because it is the time when the days are very hot and, in the presence of high humidity, clouds of great vertical development of the Cumulonimbus (Cb) type are formed, which can reach up to 15 to 20 kilometers. tall and are capable of generating destructive wind.

On its website, the National Weather Service from the United States explains what a downburst is – a violent downward current of wind – which is capable of producing damage and damage as serious as that of a tornado due to the enormous speed that the wind can reach during episodes of this type of phenomenon.

“A downburst is a strong, relatively small area of ​​rapidly descending air beneath a thunderstorm that can result from very strong high-altitude wind being transported to the surface. Or it could be the effect of very rapid cooling of the air with rain that evaporates in an initially dry atmosphere. Cooler, denser air quickly sinks to the surface.

A downburst differs from a typical thunderstorm wind in its potential to cause damage near the surface, where it spreads or diverges considerably. On the contrary, in tornadoes they converge on a narrow strip of land.

Intense downbursts can be phenomenal. Wind speeds can reach marks as high as those observed at Morehead City (North Carolina) and 254 km/h at Andrews Air Force Base (Maryland). Strong downburst episodes can cause sounds and noises that people often refer to as coming from a freight train, a term typically associated with tornadoes.

Although downbursts are not tornadoes, they can cause damage equivalent to a small or medium tornado, after all, wind is wind. Downbursts are classified as macrobursts or microbursts depending on the extent of the area affected by the wind. Damage from macrobursts extends horizontally for more than four kilometers while in microbursts the destructive winds occur in an area of ​​less than four kilometers.”

A Cumulonimbus cloud, due to its violent ascending and descending currents, within and near the cloud generates strong to severe turbulence, hail, ice formation, lightning and sometimes tornadoes, which is a risk for aircraft, especially when landing and taking off in front of the danger of wind shear and violent downdrafts (microburst).

After several plane crashes caused by downbursts in the United States, airports began to have meteorological radars and several studies were carried out in the country. The most famous case is the Delta Flight 191 disaster in which 137 people died. The aircraft was preparing to land at Dallas airport when it was hit by a microburst, an intense downdraft in a storm cloud, and the plane was sent crashing into the ground a kilometer from the runway.

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