Madagascar, the fourth largest island on Earth, lies off the southeast coast of Africa, in the western Indian Ocean. Oriented northeast to southwest, the island is bathed by southeasterly trade winds throughout the year, producing copious precipitation along its eastern coast; indeed, some areas receive up to 150 inches of rain. Since highlands run down the center of the island, the western coast of Madagascar lies in their rain shadow and its climate is much drier.
The wet season in Madagascar runs from November through April, encompassing the warmest months of the year. During the Southern Hemisphere summer, the Intertropical Convergence Zone (ITCZ) drifts south from the Equator and, from December through early March, it crosses the northern half of Madagascar. Along this zone, northeasterly and southeasterly trade winds merge, producing lift and bands of thunderstorms; the colliding winds also produce wind shear at the surface and, if upper level winds are calm, cyclones may develop. Most common from January into March, those that strike Madagascar develop east of the island, over the warm waters of the Indian Ocean, and then drift westward along the ITCZ.
This week, Cyclone Giovanna, a category 4 storm, packing winds up to 120 miles per hour, has produced devastation across the island nation, killing at least 5 persons. After crossing Madagascar, it is expected to impact Mozambique, on the African mainland.
