Extratropical Cyclone Arani in Rio de Janeiro, Brazil

Storm surge in Icaraí, Niterói

A rare extratropical cyclone swept into Rio de Janeiro, creating some monster waves and flooding the streets - including the street where I lived in Icaraí last summer (summer in Rio, winter in California).

According to NASA:

Arani has the appearance of a tropical cyclone but has been classified as a subtropical cyclone. Subtropical cyclones are low pressure areas that develop with a cold core and transition to a warm core in the mid-levels of the troposphere, resembling a tropical cyclone. They more typically form outside of hurricane season (which is June 1 to Nov. 30 in the Northern Atlantic, for example). They also have broad wind patterns and that means that their maximum sustained winds are usually located farther from the center than a tropical cyclone. They also have no weather fronts linked to them, such as a typical low pressure area that brings summertime storms with an associated cold front. Subtropical cyclones can sometimes become tropical cyclones, and occasionally, tropical cyclones can become subtropical.

Tropical cyclones are very rare in the Southern Atlantic Ocean. In 2004 a cyclone called Catarina formed in the South Atlantic and caused some controversy when it was classified as a hurricane by the United States' National Hurricane Center.

Note that Cyclone Catrina was the first ever hurricane to hit Brazil in recorded history. Arani is only the third (second official) named tropical cyclone ever recorded in the Southern Atlantic Ocean.

Things are changing - its about time we take notice so we can start taking proactive, preventative steps to mitigate against the already evident threat of climate change.


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Here is a great video of the waves crashing onto the streets throughout Rio.

Another video - you might recognize the MAC (Museum of Contemporary Art) in the background: