Cyclone Freddy
Tropical Cyclone Freddy was an extremely long-lived and destructive storm that originated in the South Indian Ocean on 4 February 2023 and persisted until 14 March 2023, achieving a duration of 36 days at tropical storm intensity or higher, the longest recorded for any tropical cyclone as verified by the World Meteorological Organization using a threshold of 10-minute sustained winds of at least 30 knots.[1][2] Originating near the northwest coast of Australia, it traversed more than 12,785 kilometers westward across the basin—equivalent to about one-third of Earth's circumference—undergoing repeated cycles of rapid intensification, including peaks as an intense tropical cyclone with estimated 10-minute sustained winds reaching 230 km/h and central pressures around 940 hPa.[1][3] The system made multiple landfalls, striking Madagascar twice, Mozambique twice, and indirectly devastating Malawi through prolonged heavy rainfall and flooding, resulting in over 1,200 deaths in Malawi alone from landslides and inundation, more than 180 fatalities in Mozambique, and additional casualties in Madagascar, with total impacts affecting millions across the region and economic losses estimated at $481 million.[1][1] Freddy's exceptional longevity and accumulated cyclone energy marked it as the highest for any Southern Hemisphere storm, highlighting unusual atmospheric conditions that sustained its vigor despite land interactions and shear.[1]
Meteorological history
Formation and initial development
A tropical disturbance associated with a low-pressure area formed northwest of Australia, south of the Indonesian archipelago, on February 4, 2023. The system benefited from favorable atmospheric conditions, including sea surface temperatures above 28°C and low vertical wind shear of 10–15 knots, which allowed for rapid organization of deep convection and a defined circulation center.[4][5] The Australian Bureau of Meteorology (BoM) began monitoring the system as Tropical Low 05U, and on February 6, 2023, it strengthened sufficiently to be named Tropical Cyclone Freddy by the BoM as it tracked westward into the South-West Indian Ocean basin.[6] Initial intensification proceeded steadily, with the storm reaching tropical cyclone intensity (equivalent to Category 1 on the Saffir-Simpson scale, with 10-minute sustained winds of at least 119 km/h) by February 8 amid continued low shear and warm ocean waters.[7] Freddy maintained a westward trajectory across the Indian Ocean, undergoing periods of rapid intensification driven by high potential intensity from elevated sea surface temperatures and minimal environmental disruption. By February 19, 2023, it had strengthened to Category 4 equivalent intensity on the Australian scale, with 10-minute sustained winds reaching 220 km/h and a central pressure near 935 hPa.[8][9] This phase marked the cyclone's initial peak before subsequent interactions with landmasses.First landfall and re-intensification
Tropical Cyclone Freddy made landfall on the southeastern coast of Madagascar near Mananjary on 21 February 2023, with maximum sustained winds equivalent to a Category 3 storm on the Saffir-Simpson scale, estimated at around 130 km/h (81 mph).[10] The system had undergone weakening prior to landfall due to interaction with Madagascar's terrain, increased vertical wind shear, and dry air entrainment, reducing its intensity from an earlier peak.[11] Over land, Freddy's core structure was disrupted, leading to rapid decay of its winds and initial dissipation of the organized circulation, though it continued to produce heavy rainfall exceeding 200 mm in some areas of eastern Madagascar.[12] After traversing Madagascar and further weakening, the remnants of Freddy re-emerged over the Mozambique Channel around 2 March 2023, where elevated ocean heat content and an influx of moist tropical air supported reorganization of the low-level circulation.[13] By 7 March, the system had begun to consolidate amid low wind shear and sea surface temperatures of 27-28°C, setting the stage for re-intensification.[14] This recovery phase featured rapid strengthening, with Freddy attaining Category 5 equivalent status by 10 March, boasting one-minute sustained winds of 260 km/h (160 mph), an exceptional rebound facilitated by the warm waters of the channel and minimal atmospheric inhibition.[15][14] The dynamics underscored the cyclone's resilience, drawing energy from high oceanic enthalpy despite prior land interaction.[5]Second landfall and peak phase
After looping southward and re-emerging into the open waters of the Mozambique Channel in early March 2023, Tropical Cyclone Freddy experienced renewed intensification driven by warm sea surface temperatures exceeding 28°C and reduced vertical wind shear, allowing it to regain tropical cyclone status.[16] Satellite observations indicated a consolidating central dense overcast with intermittent eyewall development, though the system did not reform a fully symmetric eye as pronounced as during its initial February peak.[17] Favorable upper-level divergence over the region supported sustained convection and outflow, enabling the storm to maintain intensities equivalent to a Category 3-4 on the Saffir-Simpson scale for 1-minute winds, with estimated 10-minute sustained winds approaching 120-140 km/h.[12] This phase marked an unusual persistence for a post-looping tropical cyclone in the southwest Indian Ocean basin, contrasting with typical rapid decay after such maneuvers.[14] Freddy made its second landfall in Mozambique on March 11, 2023, between 18:00 and 20:00 local time, striking the locality of Macuze in Quelimane District, Zambezia Province, as an intense tropical cyclone with maximum sustained winds of approximately 145 km/h (90 mph).[18] The storm's track brought it ashore near the coastal city of Quelimane, where it briefly traversed inland terrain characterized by low elevation and mangrove systems before curving slightly northward.[19] At landfall, the cyclone's asymmetric structure featured a tilted axis due to prior interactions with Madagascar's terrain, but its core remained dynamically active, with radar and satellite data showing embedded mesoscale convective bands.[20] This extended period of high intensity prior to and during the second landfall contributed substantially to Freddy's accumulated cyclone energy (ACE), a metric calculating integrated wind energy over time, reaching approximately 80 units by March 10 and surpassing prior records to 86 units by March 12.[14][21] The ACE accumulation during this phase alone exceeded that of many full tropical cyclone seasons, underscoring the storm's exceptional thermodynamic efficiency despite not attaining its initial peak wind speeds.[16]Dissipation over Mozambique
After crossing into Malawi on March 12, 2023, Cyclone Freddy encountered the region's hilly terrain, which disrupted its circulation through orographic effects and increased surface friction, accelerating weakening while contributing to landslides in elevated areas.[22] By March 13, sustained winds had diminished below 119 km/h (64 knots), the threshold for tropical cyclone intensity in the South-West Indian Ocean basin.[23] The remnant low-pressure system drifted southeastward into Mozambique, where continued inland propagation exposed it to persistent frictional drag from the land surface and further topographic interference from inland hills and plateaus, preventing any convective reorganization.[19] This led to complete dissipation over central-northern Mozambique on March 14, 2023, concluding a total active period of 36 days.[1][23] Although the remnants generated additional rainfall across southern Mozambique into mid-March, unfavorable vertical wind shear and lack of moist low-level inflow precluded redevelopment into a tropical system.[15]Records and exceptional features
Duration and track records
Tropical Cyclone Freddy maintained tropical cyclone intensity for 36 days from February 6 to March 14, 2023, as verified by the World Meteorological Organization (WMO) in July 2024 using a threshold of 10-minute sustained winds of at least 30 knots.[1][2] This duration surpassed the previous record held by Hurricane John in 1994, which lasted 30 days under similar criteria.[1][24] The cyclone's track covered a total distance of 12,785 km (±10 km) while at tropical storm or stronger intensity, traversing the southern Indian Ocean basin extensively.[1][2] This path length ranked as the second-longest recorded for a tropical cyclone, trailing only Hurricane John's 13,159 km.[1] Freddy made four landfalls across three countries—twice in Madagascar and twice in Mozambique—during its prolonged lifecycle, contributing to its exceptional persistence through repeated interactions with land and ocean waters.[1] The WMO's certification of these metrics has prompted updates to global tropical cyclone databases, refining thresholds for measuring system longevity and track extent based on consistent wind speed advisories.[24][1]Intensity and energy accumulation
Cyclone Freddy achieved Category 5 intensity equivalent on multiple occasions, with the Joint Typhoon Warning Center estimating peak one-minute sustained winds of 165 mph (265 km/h) prior to its first landfall in Madagascar on February 21, 2023.[4] Météo-France recorded 10-minute sustained winds up to 230 km/h and a minimum central pressure of 927 hPa during this initial intensification phase.[25] Following weakening over land and re-emergence into the Mozambique Channel, the system underwent further rapid intensification in early March, with winds estimated at up to 260 km/h by the JTWC before its second landfall in Mozambique on March 12.[5] The cyclone's energy accumulation was exceptional, as measured by its accumulated cyclone energy (ACE) index, which quantifies the integrated effect of a storm's sustained wind speeds over time using the formula ACE = Σ v_max², where v_max is the maximum sustained wind speed in knots every six hours.[12] By February 23, 2023, Freddy had already surpassed the prior Southern Hemisphere record with 66 ACE units, exceeding Cyclone Fantala's 53 units from 2016, and it ultimately set the highest ACE value ever recorded for a Southern Hemisphere tropical cyclone.[11] This metric underscores the storm's prolonged periods of high intensity across seven rapid intensification cycles, far exceeding typical cyclone behavior.[19] Sustained energy buildup was driven by favorable ocean-atmosphere interactions, including sea surface temperatures consistently above 27°C along its trajectory, which supplied latent heat and moisture fluxes essential for convective vigor and pressure falls.[23] Low vertical wind shear and a split Mascarene High further enabled these intensification episodes by minimizing disruption to the vortex and steering the system over warm waters repeatedly.[14] Such conditions highlight the role of anomalously warm Indian Ocean waters in amplifying cyclone potential energy release.[17]
Comparisons to prior cyclones
Cyclone Freddy's duration as a tropical cyclone totaled 36 days from February 6 to March 14, 2023, exceeding the prior global record of 31 days set by Hurricane John in the eastern North Pacific during 1994.[1][26] This longevity enabled Freddy to traverse over 8,000 kilometers across the southern Indian Ocean, including an unusual eastward loop that facilitated re-intensification, a feature less pronounced in shorter-lived analogs.[19] In the South-West Indian Ocean, Freddy outlasted previous extended-track systems such as Cyclone Eline in 2000, which followed a broadly similar westward path toward southern Africa but persisted for under three weeks before weakening.[27] Unlike Eline's more linear trajectory, Freddy's multi-phase evolution—marked by three distinct intensification cycles—amplified its overall energy output, with accumulated cyclone energy (ACE) reaching approximately 86 units, surpassing southern hemisphere benchmarks previously held by shorter southern systems.[16][19] Contrasting with intense but brief storms like Cyclone Idai in 2019, which generated severe impacts over roughly 10 days through rapid intensification and singular landfalls in Mozambique and Malawi, Freddy's prolonged activity resulted in repeated exposure of regions to heavy precipitation, contributing to higher cumulative rainfall in affected areas despite comparable or lower peak wind speeds.[28] Idai's ACE was substantially lower, reflecting its compressed lifecycle, whereas Freddy's extended phases underscored how duration can compound effects beyond instantaneous intensity metrics.[16] Earlier South-West Indian Ocean cyclones, such as Gafilo in 2004, achieved greater peak intensities (equivalent to Category 5) but dissipated rapidly post-landfall, limiting their basin-wide traversal compared to Freddy's record distance.[17] Satellite observations since the 1970s have enabled more precise tracking of weak or distant phases, potentially highlighting durations in modern records that pre-1980 events—reliant on sporadic ship and island reports—may have undercaptured, though Freddy's metrics remain verified extremes under contemporary standards.[1]Forecasting and preparations
Meteorological predictions and accuracy
The Joint Typhoon Warning Center (JTWC) and Météo-France's Regional Specialized Meteorological Center (RSMC) in La Réunion provided pre-landfall forecasts for Cyclone Freddy, with Météo-France issuing advisories that accurately anticipated its strengthening to very intense tropical cyclone status by February 19, 2023, and landfalls in Madagascar on February 21 and Mozambique on February 24 and March 11.[6] JTWC forecasts similarly projected a west-southwestward track toward central Madagascar within five days from mid-February, aligning with observed paths despite the cyclone's unusual looping trajectory.[29] Track predictions from global models like ECMWF demonstrated skill, with day-5 errors averaging 100-150 km, benefiting from enhanced ensemble resolution upgrades to 9 km in the Integrated Forecasting System (IFS) Cycle 48r1 tested during the event.[30] However, mean track errors escalated to approximately 177 km for days 3-5 and 284 km for days 5-7, surpassing benchmarks from the National Hurricane Center's 2023 Atlantic basin forecasts, particularly as Freddy's persistence in the Mozambique Channel deviated from typical dissipation patterns.[5] Intensity forecasts underestimated peak strengths and re-intensification episodes, with global models predicting premature dissipation in about 23.5% of cases and struggling to capture post-February 2, 2023, strengthening over the Mozambique Channel despite identifying potential for re-emergence as a tropical cyclone by early March.[5] ECMWF ensembles highlighted persistence factors such as interactions with the Mascarene High but remained under-dispersive, failing to fully account for underestimated high-pressure strength and cyclone size (optimal radius 400-600 km), which contributed to errors beyond five-day lead times.[5][30] Overall, while ensemble models provided 72-hour lead times for Category 5-equivalent warnings in high-risk zones like the Mozambique Channel, the cyclone's record 36-day duration exceeded model projections by over a week in extended forecasts.[5][6]National government measures
In Madagascar, the national disaster management agency, Bureau National de Gestion des Risques et des Catastrophes (BNGRC), oversaw preparations for Cyclone Freddy's first landfall on 21 February 2023 near Mananjary in Vatovavy-Fitovinany Region, incorporating experience from Cyclone Batsirai's impacts in 2022 to preposition supplies and designate shelter sites in high-risk coastal and lowland areas.[31] These measures emphasized awareness campaigns and evacuation to sturdy public buildings, though rural areas faced challenges in dissemination due to sparse mobile coverage and reliance on community networks.[32] Mozambican authorities in Inhambane Province conducted mass evacuations from shoreline communities ahead of Freddy's initial landfall on 24 February 2023 near Vilanculos, limiting fatalities despite heavy rains and infrastructure strain.[33] As the system reintensified offshore, the National Institute for Disaster Management (INGD) escalated alerts and evacuated over 20,000 residents to accommodation centers in Inhambane, Gaza, and Sofala provinces by mid-March 2023, prior to the second landfall on 11 March near Quelimane.[34] A red alert status facilitated rapid deployment of local response teams, though uneven road access in rural zones constrained full preemptive relocation.[35] In Malawi, warnings were disseminated via community radio stations to southern districts ahead of the storm's prolonged rainfall from 12 March 2023, compensating for limited electricity and mobile infrastructure in rural areas where compliance remained partial due to skepticism and logistical barriers.[36] The government lacked a formalized national evacuation protocol, relying instead on district-level advisories to move vulnerable populations to higher ground, with airlift options unavailable for widespread use.[37] President Lazarus Chakwera declared a state of disaster on 14 March 2023 across 10 southern districts, enabling resource allocation for immediate logistics without prior mandatory relocations.[38][39]International and regional alerts
The World Meteorological Organization's Regional Specialized Meteorological Centre (RSMC) in La Réunion, operated by Météo-France, issued tropical cyclone bulletins for Freddy beginning in early February 2023 as the system developed in the southwest Indian Ocean basin, providing advance forecasts of its track toward Madagascar and subsequent re-intensification.[19] These international advisories were disseminated through global meteorological networks, including coordination with national services in affected regions, and informed the Global Disaster Alert and Coordination System (GDACS), which classified Freddy under an overall red alert for high humanitarian impact based on projected wind speeds exceeding 253 km/h, exposed populations, and vulnerability indices.[40] By March 8–10, 2023, RSMC bulletins escalated warnings for the cyclone's third landfall potential in Mozambique, emphasizing risks of severe tropical storm conditions extending into Malawi and southern Africa.[41][42] Regional coordination involved cross-border alert mechanisms under frameworks like the Southern African Development Community (SADC), with warnings highlighting Malawi's heightened vulnerability due to saturated soils from prior seasonal rains and earlier cyclone passages.[43] Dissemination occurred via SMS mass alerts in Mozambique, reaching millions through platforms like Datawinners for rapid community mobilization, and community-based networks such as WhatsApp groups in Malawi for timely messaging to rural populations.[44][45] However, coverage remained constrained in remote, low-connectivity areas, limiting reach despite international and regional efforts.[46]Physical impacts
Mascarene Islands and initial Madagascar effects
Tropical Cyclone Freddy passed approximately 140 km northwest of Mauritius on 20 February 2023, generating strong winds and dangerous sea conditions across the Mascarene Islands, including Réunion and Mauritius.[47] Gusts reached up to 120 km/h near Mauritius, with the cyclone's outer bands producing minor flooding and limited structural impacts due to its northward trajectory.[48] Effects on Réunion were similarly restrained, featuring localized heavy rainfall and wind damage without widespread devastation.[11] On 21 February 2023, Freddy made initial landfall on Madagascar's eastern coast near Mananjary as a Category 3-equivalent system, with sustained winds of 130 km/h and gusts up to 185 km/h.[49] The cyclone delivered intense rainfall and powerful winds that caused river overflows in the Mananjary region and flattened crops through wind shear and waterlogging.[10] Storm surges were constrained to 2-3 meters along vulnerable coastal stretches, resulting in erosion but limited inundation inland.[50]Second Madagascar landfall damage
After reintensifying in the Mozambique Channel, the remnants of Tropical Cyclone Freddy generated heavy rainfall across Madagascar from early March 2023, particularly between March 5 and 10, causing secondary flooding in southeastern and southern districts already vulnerable from the initial February landfall.[22] This event exacerbated inundation in low-lying areas, with sodden ground from prior saturation leading to rapid overflow of rivers and drainage systems.[43] Government assessments reported over 3,300 homes either destroyed or flooded due to these rains, displacing more than 3,100 residents in affected localities.[13] Infrastructure in rural southern districts faced further strain, including damage to local roads and bridges from prolonged water exposure.[43] Agricultural impacts included inundation of rice paddies and other staple crop fields, with NASA Global Precipitation Measurement data verifying widespread flooded extents exceeding 100 mm of accumulated rain in parts of the southeast.[22] However, post-event analyses indicated limited overall sectoral damage, under 5 percent of projections, as the timing allowed opportunities for crop replanting in resilient varieties.[51]Mozambique wind and surge destruction
Cyclone Freddy made its second landfall near Quelimane in Zambezia Province, Mozambique, on March 11-12, 2023, with sustained winds reaching 167-175 km/h at entry. Gusts likely exceeded 200 km/h, contributing to structural failures including ripped-off roofs and partial collapses of buildings in coastal areas. Power lines were extensively damaged, with reports of widespread outages due to toppled poles and transformers disrupted by high winds.[52][53] Storm surges estimated at up to 2.36 meters inundated low-lying coastal zones, flooding infrastructure around the port of Quelimane and causing erosion along vulnerable shorelines. Post-storm assessments by the National Institute for Disaster Management confirmed damage to roads and bridges from combined wind and surge forces, with debris from uprooted structures exacerbating coastal scouring. Deforestation in the region amplified surge-induced erosion by reducing natural barriers, as verified by hazard footprint analyses.[52][54][28]Malawi flooding and landslides
Heavy rainfall from the remnants of Cyclone Freddy, affecting southern Malawi from March 12 to 15, 2023, triggered flash floods and landslides, distinct from wind-driven damage in coastal regions.[55][56] Cumulative precipitation exceeded 400 mm in 48 hours in parts of the region, leading to rapid hydrological responses including lake level rises and river overflows.[19] This intensity, equivalent to six months' rainfall compressed into six days in affected zones, overwhelmed drainage systems and saturated soils, amplifying runoff on slopes.[57] Flash floods on March 13 initiated multiple debris flows and landslides, particularly in Blantyre, Chiradzulu, Mulanje, and Phalombe districts, where steep terrain channeled water and sediment into low-lying areas.[56] In Chiradzulu and Blantyre, hill-slope mudflows descended into foothills, exacerbating inundation beyond typical riverine flooding.[37] A massive mudslide in Njuli village buried structures under debris, illustrating how localized topography intensified downslope hazards.[58] Water levels in major rivers like the Shire and Thuchila surged, with sustained high flows persisting into March 20 due to upstream accumulation.[20][59] Lake Malawi experienced notable level rises from the deluge, contributing to broader overflows in connected floodplains and wetlands.[60] These events highlighted vulnerabilities tied to floodplain settlement patterns, where prior development in high-risk zones—without adequate mitigation—concentrated exposure compared to historical floods of lesser rainfall volume.[28] Unlike earlier incidents, such as seasonal overflows, Freddy's prolonged stationary remnants produced sustained extremes, with saturated antecedent soils from February rains reducing infiltration capacity and boosting surface flow velocities.[56][61]Other mainland African regions
In eastern Zimbabwe, spillover rainfall from Cyclone Freddy's prolonged interaction with Mozambique generated localized flooding, particularly in northeastern districts, with accumulations reaching 250 to 500 mm over affected areas.[18] This exacerbated seasonal river swelling but resulted in minimal wind damage and no verified structural collapses or fatalities directly linked to the storm.[19] The peripheral effects underscored the cyclone's extended moisture plume rather than direct tropical force impacts. Southeastern Zambia experienced similar indirect heavy rains from Freddy's outer bands, prompting warnings of potential flooding in northeastern provinces with average wind speeds contributing to localized disruptions.[62] Rainfall totals remained below those in core zones, with modest crop inundation reported but no exceeding 100 mm in most stations, limiting broader agricultural losses. No deaths or significant infrastructure damage were recorded, reflecting the cyclone's diminishing intensity at these margins.[19]Human and economic consequences
Casualties and displacement
Cyclone Freddy caused at least 1,000 verified deaths across affected regions, with the majority occurring in Malawi due to prolonged flooding and landslides. The Government of Malawi officially reported over 1,000 fatalities as of April 2023, encompassing confirmed deaths and those presumed from ongoing recovery efforts.[63] In addition to deaths, over 500 people remained missing in Malawi, primarily in southern districts where search operations were hampered by inaccessible terrain.[56] Injuries exceeded 2,000, with 2,186 documented cases in Malawi alone from drowning, trauma, and exposure.[56]| Country | Confirmed Deaths | Injuries | Displaced Persons |
|---|---|---|---|
| Malawi | >1,000 | 2,186 | 659,278 |
| Mozambique | 180–200 | Not specified in aggregate reports | >19,000 (initial estimates) |
| Madagascar | 17–20 | Not specified in aggregate reports | 11,000 |