Product Code Database
Very Intense Tropical Cyclone Hellen of March 2014 was one of the most powerful in the Mozambique Channel on record, as well as the most intense of the 2013–14 South-West Indian Ocean cyclone season. Hellen formed on March 26 in the northern portion of the channel, and the storm brought rainfall to coastal Mozambique while in its formative stages. While moving southeastward, it developed an organized area of convection over the center of circulation. Warm waters allowed Hellen to rapid deepening while passing south of the Comoros, with a well-defined eye forming in the middle of the thunderstorms. The cyclone attained peak intensity March 30, with maximum sustained winds estimated according to the Regional Specialized Meteorological Center, Météo-France in La Réunion. Subsequently, Hellen weakened quickly due to dry air and land interaction with Madagascar, and the storm's eye dissipated. On March 31, the storm made landfall in northwestern Madagascar as a weakened cyclone, despite previous forecasts for the center to remain over water. By April 1, Hellen was no longer a tropical cyclone after most of the convection dissipated. The remnants turned to the west, moving over Mozambique without redeveloping, later dissipating on April 5.
Early in its existence, Hellen's rainfall in Mozambique destroyed hundreds of houses and a bridge. Flooding killed four people in the country, three of whom due to a home collapsing. Later, the cyclone passed south of the Comoros islands, causing flooding due to high storm surge and waves that killed one person. The storm forced 8,956 people to evacuate their homes due to the threat for , while 901 houses were damaged or destroyed. On nearby Mayotte, high rainfall flooded rivers, sweeping one car away. In northwestern Madagascar, Hellen damaged or destroyed 611 houses, leaving 1,736 people homeless. The storm killed three people after capsizing a boat.
Though convection later began to consolidate into a small central dense overcast (CDO) feature by March 28, continued disruption of the low-level inflow prevented much development. Météo-France noted that despite forecasting the storm to peak as a moderate tropical storm, with winds of , there was potential for rapid intensification due to the storm's small size. Conversely, the JTWC noted that proximity to land and dry mid-level air, represented by surface outflow boundary, could hamper significant development. Once further over the Mozambique Channel, the system became increasingly organized and the JTWC initiated advisories on the storm as Tropical Cyclone 21S. Météo-France followed suit at 0000 UTC on March 29 and classified the cyclone as a moderate tropical storm, with the tropical cyclone warning center in Madagascar assigning the name Hellen. Hellen soon assumed an east-southeast track toward Madagascar, as a ridge established itself to the northeast. Throughout March 29, the storm became increasingly organized with an eye apparent on microwave satellite imagery.
Rapid to explosive intensification ensued during the later half of March 29 into March 30 at a rate Météo-France later referred to as "astounding". Deep convective banding wrapped around a ragged eye, which soon contracted to "pinhole" size. This prompted Météo-France to upgrade Hellen to a tropical cyclone with winds estimated at at 0000 UTC on March 30. Six hours later, they further upgraded the storm to an intense tropical cyclone with winds of . Hellen attained its peak intensity between 1100 and 1500 UTC as a very intense tropical cyclone, with winds of , gusts reaching , and a barometric pressure of 915 mbar (hPa; ). This ranked it as one of the most powerful storms over the Mozambique Channel on record. The storm featured a wide eye embedded within a symmetrical and intense CDO, spanning across. The JTWC estimated Hellen to have attained one-minute sustained winds of , making it a high-end Category 4-equivalent cyclone on the Saffir–Simpson hurricane wind scale, although this was lowered to in reanalysis.
After peak intensity, the cyclone's eye soon began to fill and cool as weakening ensued. Defying previous forecasts, Hellen continued on a southeasterly track toward Madagascar and the likelihood of it making landfall became apparent. By the end of March 30, Hellen's eye had collapsed and disappeared from satellite imagery, as the combination of dry air and land interaction took their toll on the storm. At about 0800 UTC on March 31, Hellen made landfall on Mitsinjo with winds of , and the previously unfavorable conditions coupled with land interaction to induce rapid weakening. The ridge to the east turned Hellen to a southwest drift over land. By early on April 1, the convection largely dissipated as the center became difficult to locate, with peak winds dropping to . As a result, Météo-France discontinued advisories that day, as did the JTWC. The remnants moved back over open waters, but were not expected to reorganize due to the poor nature of the convection. As the low continued to the west, the convection increased on April 4 while approaching the coastline of Mozambique, although the system failed to redevelop before moving onshore.
Though the center of Cyclone Hellen remained south of Mayotte, it prompted an "orange alert" on March 30 for the area due to the potential for hurricane-force gusts. The storm's rapid intensification caught most residents on the island off-guard, with widespread disruptions to traffic and electricity taking place. Wind gusts up to downed trees and power lines, blocking off roads while heavy rains caused significant flooding. A peak 24‑hour rainfall of was measured in Mtsamboro between March 29 and 30. In M'Tsangamouji, cars were swept away by a swollen river. Along the coast, waves up to damaged marinas in Dzaoudzi, Hagnoundrou, and Mamoudzou where were smashed against rocks or stranded.
Due to the storm affecting water access in northwestern Madagascar, there was concern for a disease outbreak, with a flu outbreak noted in Mahajanga. The national Red Cross utilized 54 volunteers to assist in the storm's aftermath, such as distributing kitchen kits and agriculture units. Residents donated 2 million Malagasy ariary ($800 USD) to the Red Cross, which were used to purchase medicines, while the government provided of rice for affected residents.
|
|
