the scope of this article is limited to the indian ocean in the northern hemisphere, east of the horn of africa and west of the malay peninsula. there are two main seas in the north indian ocean — the arabian sea to the west of the indian subcontinent, abbreviated "arb" by the india meteorological department (imd); and the bay of bengal to the east, abbreviated "bob" by the imd. the official regional specialized meteorological centre in this basin is the india meteorological department (imd), while the joint typhoon warning center releases unofficial advisories. on average, four to six storms form in this basin every season.