South-West Indian Ocean cyclone in 2019
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Intense Tropical Cyclone Idai () was one of the worst tropical cyclones on record to affect Africa and the Southern Hemisphere. The long-lived storm caused catastrophic damage, and a humanitarian crisis in Mozambique, Zimbabwe, and Malawi, leaving more than 1,500 people dead and many more missing. Idai is the deadliest tropical cyclone recorded in the South-West Indian Ocean basin. In the Southern Hemisphere, which includes the Australian, South Pacific, and South Atlantic basins, Idai ranks as the second-deadliest tropical cyclone on record. The only system with a higher death toll is the 1973 Flores cyclone that killed 1,650 off the coast of Indonesia.
The tenth named storm, seventh tropical cyclone, and seventh intense tropical cyclone of the 2018–19 South-West Indian Ocean cyclone season, Idai originated from a tropical depression that formed off the east coast of Mozambique on 4 March 2019. The storm, Tropical Depression 11, made landfall in Mozambique later in the day and remained a tropical depression through its five-day trek over land. On 9 March, the depression re-emerged into the Mozambique Channel and strengthened into Moderate Tropical Storm Idai on the next day. Idai then began a stint of rapid intensification, reaching an initial peak intensity as an intense tropical cyclone, with sustained winds of on 11 March. Idai then began to weaken, due to ongoing structural changes within its inner core, falling to tropical cyclone intensity. Idai's intensity remained stagnant for about a day or so before it began to re-intensify. On 14 March, Idai reached its peak intensity, with maximum sustained winds of and a minimum central pressure of 940 hPa (27.76 inHg). Idai then began to weaken as it approached the coast of Mozambique, due to less favourable conditions, weakening below intense tropical cyclone status later that day. On 15 March, Idai made landfall near Beira, Mozambique, subsequently weakening into a remnant low on 16 March. Idai's remnants slowly continued inland for another day, before reversing course and turning eastward on 17 March. On 19 March, Idai's remnants re-emerged into the Mozambique Channel and eventually dissipated on 21 March.
Idai brought strong winds and caused severe flooding in Madagascar, Mozambique, Malawi, and Zimbabwe, which killed at least 1,593 people – and affected more than 3 million others. Catastrophic damage occurred in and around Beira in central Mozambique. The President of Mozambique stated that more than 1,000 people may have died in the storm. A major humanitarian crisis unfolded in the wake of the cyclone, with hundreds of thousands of people in urgent need of assistance across Mozambique and Zimbabwe. In the former nation, rescuers were forced to let some people die in order to save others. A cholera outbreak ensued in the storm's wake, with more than 4,000 confirmed cases and seven fatalities by 10 April. Total damages from Idai across Mozambique, Zimbabwe, Madagascar, and Malawi were estimated to be around $3.3 billion (2019 USD), with US$1 billion in infrastructure damages, making Idai the second costliest tropical cyclone in the South-West Indian Ocean basin.
Meteorological history.
Cyclone Idai originated from an elongated circulation that the Météo-France office in Réunion (MFR) began monitoring on 1 March. At that time, it was in the Mozambique Channel and was moving west-southwest, towards Africa's east coast. The MFR continued to track the system over the next couple of days as it developed strong deep convection. On 4 March, the MFR stated that Tropical Depression 11 had formed off the east coast of Mozambique. The depression slowly moved westward, making landfall in Mozambique later in the day. The system retained its status as a tropical depression through its existence over land. Shortly after landfall, the system turned to the north. Over the next several days, Tropical Depression 11 performed a counterclockwise loop near the border of Malawi and Mozambique, before turning eastward and re-emerging into the Mozambique Channel, early on 9 March. On 8 March, at 22:00 UTC, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert (TCFA), noting a consolidating low-level circulation center and that the system was in a favourable environment with low wind shear and sea surface temperatures exceeding .
On 9 March, after Tropical Depression 11 had re-entered the Mozambique Channel, the JTWC issued its first warning on the system, classifying it as Tropical Cyclone 18S. At 00:00 UTC on 10 March, the MFR upgraded the system to a moderate tropical storm and designated it as "Idai", after an increase in organised convection and the development of banding features. Idai then began a period of rapid intensification, with the MFR upgrading it to tropical cyclone status by 18:00 UTC. At the same time, the JTWC upgraded it to the equivalent of a Category 1 hurricane on the Saffir–Simpson scale. Additionally, the strengthening of a subtropical ridge to the southwest and the weakening of the Intertropical Convergence Zone to the north resulted in a decrease in the forward motion of the storm. Around 12:00 UTC on 11 March, Idai reached its initial peak intensity as an intense tropical cyclone, the seventh storm of that intensity that season, with 10-minute maximum sustained winds of . At that time, the MFR reported that the internal structure of the cyclone had improved, with an eye visible in infrared imagery. Meanwhile, the JTWC estimated 1-minute winds of , the equivalent of a Category 4 major hurricane, although operationally, the JTWC classified Idai as a Category 3-equivalent tropical cyclone.
Soon afterward, Idai began a weakening trend as it entered an eyewall replacement cycle and experienced dry air entanglement. It was also noted that Idai was tracking towards the southwest, under the increasing influence of the subtropical ridge to the north. On 12 March at 06:00 UTC, Idai bottomed out at tropical cyclone status with 10-minute winds of . At that time, the MFR noted that Idai had a poorly defined eye, as the eyewall replacement cycle was still underway. Over the next day, Idai's intensity changed very little due to ongoing structural changes within its inner core. At the same time, Idai began to travel in a westerly direction. By 18:00 UTC on 13 March, Idai had developed a large eye and taken on the characteristics of an annular tropical cyclone. Six hours later, Idai reached peak intensity, with 10-minute maximum sustained winds of and a minimum central pressure of 940 hPa (27.76 inHg). At that time, the JTWC also reported that Idai had reached peak intensity, with 1-minute sustained winds of . Soon afterward, Idai began to weaken, due to lower sea surface temperatures and vertical wind shear as it neared the coast of Mozambique.
At 00:00 UTC on 15 March, the MFR reported that Idai had made landfall near Beira, Mozambique, with 10-minute sustained winds of . Shortly afterward, the JTWC issued its final warning on Idai, stating that the cyclone had diminishing eyewall convection and warming cloud tops. Idai quickly weakened after landfall; at 06:00 UTC that day, the MFR declared that Idai had degenerated into an overland depression, with gale-force winds as it continued to move inland. Six hours later, the MFR issued its last warning on Idai. At that time, it was forecast that Idai's circulation would persist for several more days, and would drop heavy rainfall throughout the region during that time. The MFR continued to monitor Idai for the next few days, with Idai degenerating into a remnant low late on 16 March. On 17 March, the MFR noted that only a wide clockwise circulation remained over eastern Zimbabwe, though rain from Idai's remnant was still affecting the entire region. On the same day, Idai's remnants turned eastward once again, eventually re-emerging into the Mozambique Channel a second time on 19 March. Idai's remnants encountered unfavourable conditions and rapidly weakened thereafter, dissipating late on 21 March over the Mozambique Channel.
Impact.
Idai caused severe flooding throughout Madagascar, Malawi, Mozambique, and Zimbabwe resulting in at least 1,593 deaths. More than 3 million people experienced the direct effects of the cyclone, with hundreds of thousands in need of assistance. Infrastructural damage from Idai across these countries totaled at least US$1 billion.
Mozambique.
Throughout Mozambique, Idai killed at least 602 people, injured 1,641 others, and inflicted an estimated US$773 million in damage.
First landfall.
Flooding from the precursor depression began in Mozambique on 6 March, primarily affecting north-central provinces. The Niassa, Tete and Zambezia provinces were affected, the latter being hardest-hit. Flooding from the tropical depression killed 66 people and injured 111 more. It was reported that 5,756 homes were destroyed, while another 15,467 homes were affected. Additionally, eight hospitals and 938 classrooms were destroyed. The floods also ruined of crops.
Second landfall.
During its second landfall, Cyclone Idai wrought catastrophic damage across a large swath of central and western Mozambique. Destructive winds devastated coastal communities and flash floods destroyed inland communities in what the World Meteorological Organization termed "one of the worst weather-related disasters in the southern hemisphere". At least 532 people were killed from the combined effects of flooding and wind. In Beira, airborne debris caused numerous injuries; in some instances, sheet metal from roofs decapitated people. More than 1,500 people were treated for storm-related injuries, primarily from airborne debris, in hospitals across Beira. As of 7 April, assessments indicate the destruction of 111,163 homes, damage to another 112,735 houses, and flooding to a further 15,784 structures. An estimated 1.85 million people were affected by the cyclone. Alongside damage to infrastructure, approximately of crops were damaged or destroyed nationwide. Much of this land near the landfall area was near-harvest, compounding the risk of food shortages and placing the country at high-risk of famine.
Making landfall in Mozambique near Beira, Idai produced a storm surge of in the city. Coupled with torrential rains, including earlier rainfall, disastrous flooding ensued in the region. Officials called the extensive flooded areas "an inland ocean" visible even from outer space. More than 500,000 people in the city, the majority of the population, lost power. Rainfall in the city exceeded , while the heaviest totals of more than fell near Chimoio. As of 19 March, 100,000 people were reported as requiring rescue in the Beira area. The IFRC reported that 90% of the area in Beira was totally destroyed. Communications in the city were crippled and all roads out were rendered impassable. All 17 of the city's hospitals and health centers suffered damage. The International Federation of Red Cross and Red Crescent Societies described damage in the region as "massive and horrifying" and the President of Mozambique stated that over 1,000 people may have died. Bodies were found floating in floodwaters in Beira days after the storm hit.
A tsunami-like wave of water devastated Nhamatanda, sweeping many people to their deaths and destroying the town. People scrambled to rooftops in order to survive. Days after landfall, the Buzi and Pungwe rivers in central Mozambique overflowed their banks. Unprecedented flooding ensued along the banks of the Buzi River. President Filipe Nyusi stated "whole villages [disappeared]" along the Buzi and Pungwe banks. On 17 March, rivers in the western provinces of Mozambique were hit with floodwaters from rising rivers. The city of Búzi continued to flood as of 20 March, placing its 200,000 residents at high-risk. On 19 March, a section of the Buzi remained flooded. Thousands of people remained trapped on rooftops four days after Idai made landfall. Floodwaters estimated to be submerged entire communities.
Malawi.
Following its first landfall, Idai brought torrential rains to southeastern Malawi as a tropical depression. These areas saw above-average rainfall in January, enhancing the risk for floods. Widespread flooding began on 9 March, washing out bridges, roads, and destroying numerous homes. Fourteen districts experienced direct effects from the storm, with Nsanje and Phalombe being hardest-hit. Rising waters overwhelmed flood mitigating infrastructure, causing dams to collapse. Approximately 1,400 homes were destroyed in Blantyre. After Idai made its second landfall in Mozambique on 15 March, the storm caused even more damage in the region. Two hydroelectric power plants along the Shire River suffered damage and were taken offline, rendering a loss of 270 MW of Malawi's 320 MW hydroelectric power capacity.
The disaster directly affected 922,900 people nationwide–an estimated 460,000 being children–125,382 of whom were displaced or rendered homeless. A total of 60 people were killed and 577 others were reported injured as a result of flooding. A further three people are reported missing.
Madagascar.
While over the Mozambique Channel, the system brought heavy rains to northwestern Madagascar, with localised accumulations of approximately . Flooding and mudslides in Besalampy killed one person, left two missing, and affected 1,100 others, as well as damaging 137 homes. Widespread