Tropical Cyclone Freddy may set new record

The World Meteorological Organization is setting up an expert committee to evaluate whether tropical cyclone Freddy has broken the record as the longest-lasting tropical cyclone on record. It has been a named tropical cyclone for 34 days, crossed the entire South Indian Ocean and travelled more than 8,000 kilometers. The accumulated cyclone energy (index used to measure the energy released by a tropical cyclone) is the equivalent of an average full North Atlantic hurricane season.

There are major socio economic and humanitarian impacts but accurate early warnings by National Meteorological and Hydrological Services and coordinated disaster management on the ground prevented even greater loss of life, thus underlining the paramount importance of Early Warnings for All. Initial unconfirmed reports spoke of 190 deaths. 

Freddy made landfall in northern  Mozambique in of the province of Zambezia  on 11 March, according to the National Meteorological Hydrological Service (INAM). This is the second time Freddy has made landfall in Mozambique.  

Destructive winds, storm surge and extreme rainfall have hit large areas including Northeast Zimbabwe, Southeast Zambia, Malawi and Mozambique.

Rainfall is expected to total 200 to 300 mm and as much as 400-500 mm over the landing area of Mozambique and in the mountainous areas, generating likely severe floods.. This is more than twice the usual monthly rainfall in a matter of days. 

Malawi may receive cumulative rainfall in the order of more than 300 to 400 mm in 48 hours, causing widespread flooding and flash flooding. Malawi’s Department of Climate Change and Meteorological Services advised people to move to higher ground, follow any evacuation orders and to avoid rivers. It warned of the risk of collapse of houses and pit latrines, and power lines.

The ongoing rainfall will exacerbate flooding from Freddy’s first passage and from heavy seasonal rains which mean that rivers are full and ground is sodden. Southern Mozambique received more than a year's worth of rainfall in the past month, and Madagascar got three times the monthly average in the space of a week.

The storm first made landfall in Madagascar on 21 February and in Southern Mozambique on 24 February. It spent several days tracking over Mozambique and Zimbabwe, bringing heavy rains and flooding. It then looped back towards the Mozambique Channel and picked up energy from the warm waters and moved towards the south-western coast of Madagascar and then back towards Mozambique.

Early Warnings for All

"Freddy is having a major socio-economic and humanitarian impact on affected communities. The death toll has been limited by accurate forecasts and early warnings, and coordinated disaster risk reduction action on the ground - although even one casualty is one too many," said Dr Johan Stander, WMO Services Director.

"This once again underlines the importance of the UN Early Warnings for All initiative to ensure that everyone is protected in the next five years. WMO is committed to working with our partners to achieve this and tackle extreme weather and climate change related risks - one of the biggest challenges of our times," he said.

Advance warnings of the storm by to WMO’s Regional Specialized Meteorological Centre La Réunion (Meteo-France) and by the national meteorological and hydrological services of Madagascar, Mozambique and Malawi allowed the disaster management and humanitarian communities to mobilize in advance, with evacuations and pre-positioning of food supplies. 

Four people have died in Madagascar due to the latest rains, bringing Freddy’s death toll to least 21 people (10 in Mozambique and 11 in Madagascar), according to the  report from OCHA on 6 March. The Malawi Red Cross Society said that 66 people have died in Malawi, 93 injured and 16 people as of 13 March, amid a massive search and rescue operation.

Mozambique’s national disaster management agency INGD estimates that 1.75 Million people have been affected, with over 8,000 persons displaced.

Potentially record-breaking storm 

Meteorologically, Freddy has been a remarkable storm. The Australian Bureau of Meteorology, which acts as a WMO regional centre, named Freddy on 6 February a few hundred kilometers off the northwest coast of Australia.

Freddy tracked across the entire Indian Ocean from east to west, affecting Mauritius and La Réunion on its long journey en route to Madagascar. This kind of super zonal track is very rare. The most recent recorded cases were Tropical Cyclones Leon-Eline and Hudah, both in 2000, which like 2023 was a la Niña year.

WMO is monitoring whether Freddy will set a new record as the longest lasting tropical cyclone. It is likely that the WMO Weather and Climate Extremes evaluation committee will set up an investigation AFTER the cyclone has dissipated.

"The WMO Weather and Climate Extremes Archive are currently assembling a blue-ribbon international committee of scientists. Once the tropical cyclone has dissipated, these experts will begin a detailed examination of the raw data to determine if Freddy has indeed established a record as the longest-duration tropical cyclone on record.  One question that we will be addressing is the fact that throughout its long lifetime, the storm has periodically weakened below tropical storm status.  We will obviously need to address if that is a concern in our evaluation," said Prof. Randall Cerveny, WMO Weather and Climate Extremes rapporteur. 

"Our evaluations are detailed scientific inquiries so they do take time," he said.

The current record is held by Hurricane/Typhoon John, which lasted 31 days in 1994.

According to NASA, Freddy has set the record for having the highest accumulated cyclone energy (ACE) of any southern hemisphere storm in history. ACE is an index used to measure the total amount of wind energy associated with a tropical cyclone over its lifetime.

The WMO Weather and Climate Extremes Archive gives details of records for temperature, precipitation, wind speed and more.

"World record or not, Freddy will remain in any case an exceptional phenomenon for the history of the South-West Indian Ocean on many aspects: longevity, distance covered, remarkable maximum intensity, accumulated cyclone energy (ACE) amount, impact on inhabited lands ... but it will be necessary to wait until the system ends its life cycle to make an exhaustive assessment," said Sebastien Langlade, Head of Operations at RSMC La Réunion.

Role of climate change

According to the Intergovernmental Panel on Climate Change (IPCC), for East Southern Africa and Madagascar, there are observed and projected increases in heavy precipitation and pluvial flooding. There is a projected increase of average tropical cyclone wind speeds and associated heavy precipitation and of the proportion of category 4-5 tropical cyclones.

Globally, rising mean sea levels will contribute to higher extreme sea levels associated with tropical cyclones. Coastal hazards will be exacerbated by an increase in the average intensity, magnitude of storm surge and precipitation rates of tropical cyclones. There is low confidence in changes in the future frequency of tropical cyclones at the global scale.