Meteorological history of Cyclone Freddy

Very Intense Tropical Cyclone Freddy

Very intense tropical cyclone (SWIO scale)
Category 5 tropical cyclone (SSHWS)
Track of Cyclone Freddy, according to the Saffir-Simpson scale
Formed	4 February 2023
Dissipated	Currently active
Duration	5 weeks and 3 days
Highest winds	10-minute sustained: 220 km/h (140 mph) 1-minute sustained: 270 km/h (165 mph)
Lowest pressure	931 hPa (mbar); 27.49 inHg
Areas affected	Mascarene Islands Madagascar Mozambique Zimbabwe Malawi
Part of the 2022–23 Australian region and South-West Indian Ocean cyclone seasons

Cyclone Freddy is the longest-lived tropical cyclone on record, beating the previous record of Hurricane John in 1994. It also has the highest accumulated cyclone energy (ACE) of any tropical cyclone on record worldwide, surpassing Hurricane Ioke in 2006. Additionally, Freddy is the only known tropical cyclone to achieve seven separate rapid intensification cycles. While in the Australian region cyclone basin, the storm quickly intensified and became a Category 4 severe tropical cyclone, before it moved into the South-West Indian Ocean basin. The Joint Typhoon Warning Center (JTWC) estimated Freddy's peak strength, equivalent to Category 5 strength on the Saffir–Simpson scale. During 19 February, Météo-France (MFR) upgraded it to a very intense tropical cyclone. Freddy made its first landfall near Mananjary, Madagascar.

Freddy rapidly weakened overland but re-strengthened in the Mozambique Channel. Soon afterward, Freddy made its second landfall just south of Vilankulos, Mozambique. On 2 March, the remnant low of Freddy began to acquire tropical characteristics after re-emerging into the channel. Soon after, Freddy intensified, becoming a tropical cyclone. Then, Freddy made its third landfall in Quelimane, Zambezia Province, Mozambique.

Origins

Cyclone Freddy starting to intensify off the coast of Western Australia on 7 February

During 30 January, the Australian Bureau of Meteorology (BoM) began monitoring a developing weak tropical low embedded within a monsoon trough in Timor Sea. The disturbance was assigned the official identifier code 13U. Environmental conditions were assessed as being marginally conducive for tropical cyclogenesis. By 4 February, the BoM reported that the disturbance had developed approximately 770 km (480 mi) north-northwest of Broome in Western Australia. During 6 February, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert (TCFA) on the system. By 09:00 UTC, the JTWC initiated advisories on the system and classified it as Tropical Cyclone 11S. The BoM reported that the tropical low had developed into a Category 1 tropical cyclone on the Australian tropical cyclone intensity scale and named it Freddy.

Later that next day, feeder bands were covering its very broad and central dense overcast (CDO), prompting the JTWC to upgrade the system to a Category 1-equivalent cyclone. The BoM subsequently followed suit and upgraded Freddy into a Category 2 tropical cyclone. Freddy attained Category 3 cyclone. Freddy began showing an eye feature seen in microwave imaging, with Freddy later becoming a Category 2-equivalent cyclone. Freddy weakened slightly due to CDO and a persistent area of cold cloud tops. Weakening occurred as the JTWC assessed that Freddy's winds bottomed out at 150 km/h (90 mph). Freddy weakened back into a tropical storm, and the BoM estimated winds of 100 km/h (65 mph), the weakening resulting from easterly wind shear.

Crossover, rapid deepening, and first landfall

Cyclone Freddy as seen from the International Space Station on 20 February

Continuing to rapidly intensify, Freddy intensified, becoming a Category 3-equivalent cyclone around 15:00 UTC on 11 February. Freddy had further intensified to a Category 4 severe tropical cyclone due to the presence of a well-defined eye surrounded by deep convection. Freddy intensified into a Category 4-equivalent cyclone with a symmetric CDO. According to the JTWC, Freddy gradually became disorganized, with its eye no longer well-defined, and Freddy fell to 185 km/h (115 mph) winds. The BoM also reported that Freddy's winds weakened to 155 km/h (100 mph) of winds. Despite easterly vertical wind shear, Freddy maintained a symmetric convective core. The cyclone's ragged and cloud filled eye appeared on satellite imagery. At 12:00 UTC on 14 February, Freddy crossed 90° E into the South-West Indian Ocean basin, and was immediately classified as a tropical cyclone by Météo-France (MFR) The MFR upgraded the system to an intense tropical cyclone.

Freddy exhibited highly symmetrical and annular characteristics around 03:00 UTC on 15 February. Later the next day, the JTWC also assessed Freddy as having 1-minute maximum sustained winds of 270 km/h (165 mph), making the storm a Category 5-equivalent tropical cyclone, as the cyclone sustained a symmetric ring around deep convection. During 18 February, Freddy began to rapidly deteriorate as a sudden spike in mid-level shear began impacting the storm. As a result, the cyclone briefly weakened to 1-minute sustained winds of 205 km/h (125 mph) before restrengthening once again. Later that next day, Freddy was upgraded to a very intense tropical cyclone. Shortly afterward, Freddy's cloud pattern slightly deteriorated, causing the cyclone to weaken to an intense tropical cyclone by 00:00 UTC on 20 February. Freddy passed north of Mauritius, Réunion and weakened to a tropical cyclone on 21 February. At about 7 p.m. local time that day, the cyclone made its first landfall near Mananjary, Madagascar. After landfall, Freddy was re-classified as an overland depression, with sustained winds of 110 km/h (70 mph). The JTWC also reported that Freddy substantially weakened as it traversed the mountainous terrain of Madagascar, and was downgraded to 130 km/h (80 mph).

Re-strengthening, second landfall, and weakening

Severe Tropical Storm Freddy nearing Mozambique on 24 February

During 22 February, Freddy significantly improved in organization as it moved southwestward across the Mozambique Channel. Later that day, Freddy re-strengthened into a zone of disturbed weather. Freddy had re-developed under the deep convection in the northern semicircle of the circulation. Freddy re-strengthened into a moderate tropical storm after the convection began to rapidly increase. The system passed to the north of Europa Island. Freddy re-strengthened further, marking its intensification into a severe tropical storm. Freddy continued to organize with convective bands wrapping into the center.

Six hours later, cloud pattern deteriorated, as it approaching the coast of Mozambique. By 12:00 UTC on 24 February, the MFR reported that Freddy had made second landfall in Mozambique (and first landfall overall) south of Vilankulos, Mozambique with 10-sustained winds of 85 km/h (50 mph). Shortly after the landfall, the JTWC discontinued warnings on the system. Freddy rapidly weakened as it moved westward and further inland, weakening to an overland depression by 18:00 UTC that day. The MFR determined that Freddy convective activity was located in the southeast semicircle. Even though the MFR stopped issuing advisories on 25 February, they were still monitoring and predicted that the remnant low would likely re-develop into a tropical system.

Re-development and third landfall

Cyclone Freddy off the coast of Madagascar on 7 March

During 1 March, Freddy re-emerged into the Mozambique Channel, the JTWC resumed monitoring and stated the system had the potential to re-develop. Environmental conditions were assessed as being marginally conducive for tropical cyclogenesis, with low vertical wind shear and moderate equatorial outflow. During 2 March, Freddy observed an increase in deep convection in the eastern semicircle, prompting MFR to classify the storm as a tropical disturbance again. Microwave imagery revealed that Freddy convection was gradually wrapping around the southern periphery of the circulation. Later that next day, Freddy was downgraded to zone of disturbed weather status by the MFR. Multispectral animated satellite imagery partially revealed an exposed low-level circulation center (LLCC) with deep convection persisting along the eastern periphery of the LLCC. As a result, the JTWC re-issued a TCFA by 21:00 UTC that day. Freddy showed signs of intensification as it approached the system's estimated center, the MFR upgraded the system to a tropical depression. Freddy strengthened into a moderate tropical storm as the ASCAT-C pass featured below gale-force winds on its southern quadrant. Six hours later, Freddy gained tropical storm strength yet again with under the influence of a persistent area of convection. The convection continued to decrease, and Freddy was better organized through the LLCC. Freddy gradually improved its convection with improvements in further consolidation.

Cyclone Freddy nearly stationary while off the coast of Mozambique on 11 March.

By 18:00 UTC on 5 March, Freddy strengthened to severe tropical storm as it accelerated eastward toward the coast of Madagascar. The convection wrapped around the system's LLCC and the system gradually consolidated. Freddy began to show an ill-defined eye that was visible on satellite imagery. During 7 March, Freddy had become a tropical cyclone status with sustained winds of 130 km/h (80 mph), while the JTWC estimated that its 1-minute sustained winds reached 155 km/h (100 mph). Six hours later, Freddy continued to interact with a mid-troposphere shear. Freddy fell to severe tropical storm status later that next day. The cyclone then rapidly weakened as a result of the presence of higher wind shear as well as dry air intrusion. Later, the storm weakened to 110 km/h (70 mph). Despite the shear, convection intensified near the center as banding features improved. The Dvorak analysis indicated that Freddy strengthened into 120 km/h (75 mph). The cyclone had a well-defined eye within the storm's compact and symmetrical CDO. During 11 March, Freddy made its third landfall (and second landfall overall) on Quelimane, Zambezia Province, Mozambique with sustained winds of 150 km/h (90 mph).

The JTWC subsequently issued a final warning on the system three hours later. As the cyclone's eye disappeared from satellite imagery, Freddy weakened into a severe tropical storm. Six hours later, Freddy's cloud pattern deteriorated, with the storm weakening back into a moderate tropical storm. Freddy weakened to an overland depression with sustained winds of around 55 km/h (35 mph). At 12:00 UTC on 13 March, the MFR issued its last advisory on the storm.

Records

Cyclone Freddy holds the record for the longest-lasting tropical cyclone worldwide in recorded history. Freddy also holds the record for the all-time highest accumulated cyclone energy of a tropical cyclone worldwide, with an ACE of 87.01, breaking the former record of 85.26, set by Hurricane Ioke in 2006. Additionally, Freddy was the first tropical cyclone to undergo seven separate rounds of rapid intensification. Prior to Freddy, no storm in the Southern hemisphere had rapidly intensified more than three times.

In the Northern Hemisphere, only three storms appear to have experienced four bouts of rapid intensification, including Hurricane Norman in 2018, Hurricane Emily in 2005, and Hurricane John in 1994. The World Meteorological Organization (WMO) will conduct a formal investigation to determine whether Freddy tied or surpassed John's record. Freddy was one of only four systems—the others being cyclones Litanne in 1994 and Leon–Eline and Hudah in 2000—to travel the entirety of the southern Indian Ocean.

See also

• List of tropical cyclone records
• List of South-West Indian Ocean very intense tropical cyclones
• List of Category 4 Australian region severe tropical cyclones
• Tropical cyclones in the Mascarene Islands
• Hurricane John (1994) – The second longest-lasting and the farthest-traveling tropical cyclone ever observed.
• Hurricane Dora (1999) – One of few tropical cyclones to track across all three north Pacific basins.
• Hurricane Ioke (2006) – The second-highest accumulated cyclone energy (ACE) recorded in history.
• Cyclones Katrina and Victor–Cindy (1998) – An extremely long-lived tropical cyclone in the South Pacific that eventually regenerated into another cyclone in the Indian Ocean

External links

• MFR Track Data of Very Intense Tropical Cyclone Freddy (in French)
• JTWC Operational Track Data of Tropical Cyclone 11S (Freddy)
• 11S.FREDDY from the United States Naval Research Laboratory