Malawi, Madagascar and Mozambique are reeling from the effects of Tropical Cyclone Freddy.
More than 400 people were killed and thousands of homes destroyed.
Freddy was one of the longest lasting storms on record in the Southern Hemisphere, if not the entire world.
Southern Africa is often battered by cyclones and tropical storms from the Indian Ocean, but Freddy was different for several reasons.
How long did Freddy last?
Freddy was eventually declared dead by the French meteorological service. The storm was named by the Australian Bureau of Meteorology on February 4 and finally ended on March 14.
It was strong enough to be officially classified as a tropical system for at least 36 days.
However, we have to wait for confirmation from the World Meteorological Organization before we can say if this is officially the longest recorded storm.
What’s interesting about Freddy is how far he’s come. It began its journey off the coast of northwest Australia, crossing the southern Indian Ocean from east to west, one of only four storms in history to do so.
How powerful was Storm Freddy?
The classic way to measure the strength of a storm is by wind speed. At its strongest, Freddy was the equivalent of a Category 5 hurricane with winds exceeding 160 mph (260 km/h).
Luckily it was most intense over open water.
Freddy broke the all-time accumulated hurricane energy (ACE) record in the Southern Hemisphere, a measure of storm strength over time, beating the previous record, set by Cyclone Fantala in 2016.
It was also the first storm in the Southern Hemisphere to experience four separate cycles of rapid intensification – this is an increase in the maximum sustained winds of a tropical cyclone by at least 30 knots in just 24 hours.
Since landfall, rainfall amounts have exceeded 600mm (24 inches) in some areas with torrential downpours resulting in mudslides in vulnerable areas.
With hurricane-force winds, the storm also brought strong storm surges as it continued to replenish over the warm waters of the Mozambique Channel.
What is the difference between a cyclone and a tropical storm?
A tropical cyclone in the Indian Ocean is stronger than a tropical storm.
Freddy first hit Mozambique as a moderate tropical storm. Its second landfall in Mozambique was a tropical cyclone and by the time it reached Malawi it had weakened to tropical storm strength – although that was where it caused the most destruction .
What will Storm Freddy do next?
Freddy has now separated, but his remains continue to cause rain in parts of Mozambique and Malawi, which could worsen the flooding situation.
What is the difference between a cyclone, a typhoon and a hurricane?
These are all huge storms, but their definition depends on where they formed. In the Atlantic and Eastern Pacific they become hurricanes, in the Western Pacific they are typhoons, and in the Indian Ocean and near Australia they are called cyclones.
Was Storm Freddy caused by climate change?
That’s a tricky question to answer because Freddy is certainly unusual.
We have seen this type of storm before when we have seen a strong or persistent La Nina weather pattern in the Indian Ocean. The Bureau of Meteorology has just declared the end of a series of back-to-back La Nina events that began in September 2020.
In terms of climate change, it’s a well-known fact that warmer air can hold more water, so the amount of rain that fell, particularly while it was on land, was likely enhanced by climate change.
Warmer ocean waters contain more energy, so it follows that these storms may well become more energetic over time and be able to unleash even more precipitation.
A rapid intensification is more likely with higher sea temperatures and the fact that this has happened multiple times may be partly due to climate change. The slow movement of the storm at times, particularly just before the second landfall in Mozambique, could also be related.