Cyclone Freddy: The killer 'zombie storm' on track to become the longest ever
Cyclone Freddy is on track to become the longest-lasting tropical cyclone on record, ITV News Science Correspondent Martin Stew reports
A 'zombie storm' has left a trail of devastation, killing 100 people and destroying tens of thousands of people's homes. But while experts thought its power would dwindle, Cyclone Freddy continues to come back from the dead.
In fact, record breaking Freddy recorded more energy over its lifetime than an entire typical US hurricane season, as it rampages across the Indian Ocean.
Its powerful winds of around 100 miles an hour and the deluge of rain that have hammered countries such as Mozambique, Malawi and Madagascar have led to more than 100 people being killed.
Cyclone Freddy is on track to become the longest-lasting tropical cyclone on record, as its destructive path has continued since February 6, according to the World Meteorological Organisation (WMO).
It is now the 'strongest' storm, with it having the most accumulated cyclone energy (ACE), a measure of the storm’s strength over time, since Cyclone Loke in 2006, according to the UN.
Many scientists believe Freddy should have lost its power, but the rare weather phenomenon keeps intensifying and coming back to life as a 'zombie storm'.
Cyclone Freddy's extremely rare path of devastation
One of the key reasons Cyclone Freddy is causing so much interest is because no other tropical cyclone observed in the southern hemisphere has taken a path across the Indian Ocean in the past two decades.
It is one of only four systems which have crossed the southern Indian Ocean from east to west - the others were cyclones Litanne in 1994 as well as Leon–Eline and Hudah in 2000.
Cyclone Freddy's record breaking journey across the Indian Ocean captured by satellites
Freddy formed over a month ago on February 5 near Indonesia and barrelled a huge 4,000 miles before hitting Madagascar, according to Australian satellites monitoring its movements.
The dangerous storm hammered eastern Madagascar, before moving across the channel and slamming Mozambique.
Freddy then circling back to cause a bout of heavy rainfall in Madagascar, killing 21 people across both nations, as of Thursday.
As Mozambique struggles to recover from the destruction of over 28,000 homes, Freddy has been battering the country for a rare second time since Sunday.
According to French weather agency Météo-France's regional tropical cyclone monitoring centre in Réunion, “the heaviest rains will continue over the next 48 hours”.
Why is Cyclone Freddy causing such a stir?
As Cyclone Freddy whirls into its 35th day, an international expert task force from the WMO is being assembled to investigate why the deadly weather system has managed to survive so long.
Its re-emergence has baffled meteorologists, breaking the record to become the first ever storm to drop in intensity then regain energy seven times, as it shift of direction and batters multiple countries.
Dr Liz Stephens, a hydrologist based at the University of Reading, said: "Usually, this interaction with the land would tear apart a storm, but Freddy re-emerged in the Mozambique channel.
"This is a zombie storm that came back to life, impacted southern Madagascar again, and is now threatening central Mozambique and southern Malawi with new heavy rainfall and floods."
One of the key things the WMO expert committee wants to look into is how Freddy has dropped in energy and then rapidly intensified seven separate times, a first for a tropical cyclone in the southern hemisphere.
WMO Weather and Climate Extremes spokesperson Professor Randall Cerveny, said: "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."
The current record is held by Hurricane/Typhoon John, which lasted 31 days in 1994, which Cyclone Freddy has surpassed, if experts decide it is able to maintain its tropical storm status.
How has Cyclone Freddy managed to last so long?
While the official answer is being investigated by the WMO, there are already a few factors experts think could be helping Cyclone Freddy sustains its power.
The weather system broke the record for accumulated cyclone energy in the Southern Hemisphere, a metric to gauge a cyclone’s strength over time, on February 23.
At that time, the weather system had generated about 66 units of ACE, beating the previous record of 53, formerly held by Cyclone Fantala in 2016.
According to satellites monitoring Cyclone Freddy, it intensified seven times in a process known as eyewall replacement cycles.
"In strong cyclones, the eyewall created by dense cloud can contract and some of the outer rain bands evolve into a ring of thunderstorms that forms a new, outer eyewall," Dr Alex Baker, University of Reading and National Centre for Atmospheric Science research scientist, explains.
"This engulfs the original, and as it does the cyclone will first weaken then strengthen again. It is rare for this to happen so many times," he added.
The Met Office puts the storms longevity down to La Niña - the colder phase of the El Niño Southern Oscillation cycle.
This is when winds over the Pacific Ocean push the warm water towards America are stronger than in the warmer phase called El Niño.
It tends to make global temperatures cooler and this is the third La Niña in three successive years.
Met Office tropical cyclone expert Julian Heming said: “Leon-Eline [the second longest ever recorded cyclone] and its associated flooding happened at the end of a very long, prolonged La Niña period which also produced flooding over Mozambique.
"It looks like we could get a similar flooding situation over the next few days in Mozambique.”
Where will Cyclone Freddy hit next?
The zombie storm has risen again over Mozambique, bringing yet more heavy rainfall, high winds (hurricane strength at the centre), high seas and a large storm surge.
French weather agency Météo-France's regional tropical cyclone monitoring centre in Réunion warned Monday that “the heaviest rains will continue over the next 48 hours” as Freddy barrels on.
Mozambique’s central provinces and Malawi have been identified as especially vulnerable to “floods and landslides in mountainous areas” by weather monitors.
Freddy is expected weaken and to exit back to sea on Wednesday, according to Météo-France.
Cyclone Freddy will not hit the UK but Dr Alex Baker says the warming up of oceans make it more likely that regions outside the tropics, including the UK will be more at risk or experiencing cyclones.
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