Indian Seas, Bay of Bengal (BoB) and Arabian Sea, both have 2 cyclone seasons. Pre monsoon season between March – May and post monsoon from October to December. Monsoon months mostly remain oblivious to stormy activities, with some exceptions for June. Oceans as a rule do not have any official bounds as such and remain susceptible to freak event throughout the year.
Historic records measure the probability of likely storm in terms of track, frequency and intensity. Recently, against the least probability of storm in March, BoB witnessed tropical cyclone 01B, albeit short lived and minimal intensity. It also happened to be just 6th storm over BoB in March, since 1901. On the other side of the coast, Arabian Sea has not witnessed any storm in March. Scarcity of storms over the Arabian Sea gets extended to month of April as well.
In this century so far, between 2000 and 2021, Arabian Sea has not hosted even a single storm in April, as well. Contrarily, BoB observed 5 storms during this period and 3 of these turning extremely severe. There is no likelihood of any storm over Arabian Sea during March this year. Negating this possibility in April as well, will be too early to pre-empt and reliable prediction will be possible only beginning of the month.
With the Sun shifting to Northern Hemisphere around 20thMarch, the ITCZ also start advancing over North Indian Ocean. Most storms are propelled from this large feature of convective clouds running for thousands of kilometer. The other factors responsible for growth and sustenance being sea surface temperature and vertical wind shear. Heat potential in excess of 100 Kilo Joules becomes favorable for cyclogenesis over the oceanic surface.
During the Southwest Monsoon season, Arabian Sea is cooler than its counterpart BoB , for explicable meteorological reasons. However, similar inference during the pre monsoon may not be in order. It also means that other dynamical forces are playing bigger role to suppress cyclone formation over the Arabian Sea during March and April.
