March 29, 2023

The path taken by Cyclone Freddy across the Indian Ocean

World Meteorological Organization

The World Meteorological Organization (WMO) is considering whether tropical cyclone Freddy should be named the longest-lasting tropical cyclone on record as it clocks up its 32nd day.

“Freddy is pretty unusual,” says Liz Ritchie-Tyo at Monash University in Melbourne, Australia. Most tropical cyclones, which are low-pressure systems that form over warm tropical waters, only last for about six or seven days, she says.

Freddy originated off the north-west coast of Australia on 6 February before travelling more than 7000 kilometres across the Indian Ocean to south-east Africa.

Since making landfall in Madagascar on 21 February, the tropical cyclone has been bouncing between Madagascar, Mozambique and Zimbabwe, causing strong winds, heavy rain and flooding. It has destroyed thousands of homes and claimed more than 20 lives.

Freddy has probably lasted so long because the surrounding wind conditions have been unusually light, says Ritchie-Tyo. Normally, tropical cyclones in this region encounter strong winds that push them south over colder waters and cause them to dissipate, she says.

The current record holder for the longest-lived tropical cyclone is one called John that lasted for 31 days in the Pacific Ocean in 1994.

The WMO says it is assembling an expert committee to decide whether Freddy has broken John’s record.

Although Freddy has already lasted longer than John did, at times, it has dropped below tropical cyclone strength while passing over land.

“One question that we will be addressing is the fact that throughout its long lifetime, the storm has periodically weakened below tropical storm status,” Randall Cerveny at the WMO said in a press release. “We will obviously need to address if that is a concern in our evaluation.”

To date, Freddy has generated more than 72 units of accumulated cyclone energy – a measure of a cyclone’s strength over time. This puts it in second place behind a tropical cyclone called Ioke that generated 85 units in 2006.

Freddy has also undergone six separate periods of rapid intensification, meaning increases in wind speed of at least 30 knots in 24 hours, which is the most of any documented tropical cyclone.

Ritchie-Tyo says Freddy should finally dissipate this weekend. This is because the cyclone is already weakening and is predicted to head into dry conditions in Mozambique on Saturday morning local time, where “the friction of the land should wear the winds down”.

“I think it will die pretty quickly once it makes landfall this time,” she says.

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