The United Nations said Tuesday that cyclone winds and rain killed up to six people on Yemen's Socotra island before hitting the mainland Tuesday, the second such storm there in a week. Cyclone Megh first struck the island Sunday, injuring an estimated 60 people and damaging houses, the main power station, and hospital, the U.N. humanitarian office (OCHA) said. The storm then weakened significantly after reaching mainland Yemen's mountainous terrain on Tuesday roughly 70 kilometers east of Aden, according to the World Meteorological Organization (WMO). The U.N. agency said that a third storm could be brewing in the Arabian Sea, but those winds were expected to break up. WMO said that the highly unusual strike by two cyclones in a week was due to the "Indian Ocean dipole," a weather phenomenon similar to a regional "El Nino" effect caused by unusually warm surface water in the Arabian Sea. Megh came a week after Cyclone Chapala killed 11 Yemenis on Socotra and the mainland, dumping nearly a decade of average annual rainfall on the impoverished and war-ravaged country in just two days.