Cyclone Giovanna

Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale

Cyclone Giovanna developed from a tropical wave over the Indian Ocean heading to the southwest on February 7. The tropical disturbance soon developed into Tropical Depression 09 on February 9.[2] On the same day, the Joint Typhoon Warning Center upgraded the system, giving it the designation "12S". The storm intensified into a moderate tropical storm and was given the name Giovanna.[3] On February 10, Giovanna continued to strengthen into a severe tropical storm.[4] Later the same day, Giovanna went through a rapid intensification period and became an intense tropical cyclone, due to favorable environmental conditions.[5]

Giovanna showing a classic double eyewall signature while undergoing an eyewall replacement cycle

Soon, Giovanna began an eyewall replacement cycle[6] and weakened into a Category 3-equivalent tropical cyclone on February 11, due to high wind shear around the system.[7] However, the wind shear surrounding the storm soon weakened, and Giovanna was able to restrengthen back into an intense tropical cyclone as it finished the eyewall replacement cycle, resulting with a new, larger eye 50 kilometres (31 mi) across.[8]

At about 2200 UTC on February 13 (0100 EAT February 14), Giovanna made landfall at Andevoranto, Madagascar.[9] Giovanna then weakened into an overland tropical depression on February 14.[10] Early on February 15 Giovanna moved back out into open water, and drifted southwestward over the next few days. On February 18, Giovanna turned eastwards, and the storm was steered into warmer waters off the southern coast of Madagascar by a strong anticyclone located to the south. Giovanna strengthened into a Category 2 tropical cyclone again, and developed a small eye. However, the eye soon underwent another eyewall replacement cycle, and again began to weaken. On February 20, Giovanna entered an area of strong vertical wind shear, which displaced the system's convection to south of the circulation center and quickly weakened the system into a tropical depression.[11] On February 22, the continued strong shear caused Giovanna to degenerate into a remnant low.[12] The remnants of the storm moved further northwestward the next day, due to a Fujiwhara interaction with a stronger system to the east, Moderate Tropical Storm Hilwa, and late on February 24, Giovanna's remnants dissipated east of Madagascar.

Large waves estimated up to 8 m (26 ft) high affected the coast of Reunion and resulted in one fatality after a man was swept out to sea.[13] Another fatality took place in Mauritius after a man lost control of his motorcycle during poor weather and crashed into an electricity pylon.[14]

At least 33 people were killed by Giovanna in Madagascar.[1][15][16] Flooding and strong winds were the main destructive forces, besides the storm surge which floods many coastal areas. Thousands of people were affected by this cyclone all across Madagascar with, flooding and strong winds which mostly caused 60% of homes to be damaged or destroyed. Two villages on small islands near Madagascar were reportedly "wiped off the map." Reports indicated that 75 to 90% of structures in those areas were destroyed by the storm.[17]

Wikimedia Commons has media related to Cyclone Giovanna.

• 2011–12 South-West Indian Ocean cyclone season

• Weather Underground tracking of Giovanna