Tropical Cyclone Activity in the South Indian Ocean 2006-2007
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Following the record-breaking 2005 hurricane season, tropical storm activity in the Atlantic Basin was unexpectedly low during 2006; not a single hurricane made landfall in the United States. But as we explained in a previous issue (GEO Q11), tropical storm numbers world-wide remain remarkably constant from season to season. Recently, thanks to the full-Earth Metop coverage now available via EUMETCast, Alan Banks has been monitoring a recent surge in cyclonic activity in the Indian Ocean, impinging particularly on the island republic of Madagascar.
The southern Indian Ocean (SIO) has had a busy Tropical Cyclone season during our winter and Madagascar has born the brunt of many of the cyclones in the western SIO.
I became aware of this fairly late when Tropical Cyclone Favio developed between February 14 - 23, 2007. Favio tracked from 10° South, 70° East, travelling south west, close to Mauritius and La Reunion before rounding the southern tip of Madagascar and eventually making landfall on the coast of continental Africa close to Inharrosso in Mozambique. Favio brought very heavy rain to both Mozambique and Zimbabwe, countries that were already suffering from the effects of prolonged heavy rainfall. The Zambezi River had already broken its banks. An image I took from Metop-A as Favio made landfall (Figure 1) shows the lower Zambezi as though it were a lake rather than a river. Further study of the Australia Severe Weather website that monitors activity throughout the SIO showed that the area had already been struck by a number of storms.
Anita, Nov 29 - Dec 2, 2006
Anita was mainly a Tropical Depression but did reach typhoon status for a while. Anita tracked down the strait between Madagascar and the mainland of Africa.
Bondo, Dec 18 - 26, 2006
Bondo tracked westward from 9° South, 65° East around the north of Madagascar then moved southwest along the north west coast of the island bringing very heavy rain before making landfall close to Mahajanga.
Clovis, Dec 31, 2006 to Jan 4, 2007
Clovis made landfall close to Mananjary on the east coast of Madagascar, bringing strong winds, heavy rains and flooding to the region of Vatovavy Fitovinany.
Enok - Feb 9 - 11, 2007
Enok didn't make landfall but again brought very heavy rain to the east coast of Madagascar.
Gamede, Feb 21 - March 2, 2007
This Tropical Cyclone was immense. It didn't make landfall but passed down the east coast of Madagascar and west of La Reunion. A Meteo France satellite weather station on the neighbouring island of La Reunion claimed: ‘world records of precipitation have been beaten’ by Gamede, which brought the heaviest rainfall in 27 years. One rainfall gauge on the island recorded 47 cm of precipitation over one 3 day period. (Figure 2) shows TC Gamede northeast of Madagascar.
Indlala, March 12 - 16, 2007
Indlala (Figure 3) became the sixth cyclone of the season to hit Madagascar when it formed off the northeast coast then tracked slowly west to make landfall south of Antalaha. It then tracked inland, bringing further misery to the people of that island before losing its energy. According to reports from the Joint Typhoon Warning Centre, Indlala had winds of 115 knots (210 kph), with gusts up to 140 knots (260 kph). Wave heights were estimated to be 11 metres. The island was still picking itself up after previous storms, with the government and relief agencies already overstretched. Large areas of the northwest, west and southeast had already been flooded by torrential rains, although harvests in the south had been devastated by drought. Indlala caused at least 69 fatalities and rendered 14,000 homeless not to mention the 200,000 whose lives have been affected by storm damage. More than 3600 buildings were totally destroyed while over 8000 hectares of rice paddies were ruined.
Jaya, April 2 - 4
Tropical Cyclone Jaya, (Figure 4) which formed over the ocean on March 30, went through an explosive increase in power from tropical storm to Category-3 cyclone in just 36 hours. Fortunately, this cyclone had moderated considerably by the time it finally made landfall in the northeast of Madagascar in the early hours of April 2 ,with winds that still reached close to 150 kph, a marked change from the 200 kph just twelve hours earlier.
The 2006/7 rainy season was the first time that Madagascar had been hit by so many cyclones in such a short time and there was almost continuous rain during the three months from late December 2006. 70% of the agricultural land on the island (mainly vanilla farms and rice paddies) was flooded.Even before Indlala, the Malagasy government had launched an appeal to the international community, with the following assessment at the end of February:
• at least 7 deaths
• 32,000 victims of storm damage
• 8 thousand homeless
• 90 thousand hectares of agricultural land flooded
• 125 billion tonnes of rice harvest lost
From GEO Quarterly #14 June 2007
Australian Severe Weather Forum http://www.australiasevereweather.com/cyclones/index.html
Meteo France (La Reunion) http://www.meteo.fr/temps/domtom/La_Reunion/
Tropical Storm Risk (TSR) http://forecast.mssl.ucl.ac.uk/shadow/index_.html