Historically the Indian seas have been the deadliest basin for severe cyclones. There are two seasons for cyclonic storms – pre-monsoon (April and May) and post-monsoon (October to December). From June onwards depressions start forming, bringing monsoon showers.
The pre-monsoon month of May generally witnesses more cyclones than April. But, this April we will have no cyclone at all.
Reasons for cyclone free April, 2015
Prolonged winter rains, affecting North and Central India, could be blamed for absence of cyclones in April. This year March was the rainiest in the longest time. Consequently, temperatures were way below normal. The situation seems no different even now as unusual rains continue in North and Northeast India. By this time, heat should have started building up with dust storms being a common phenomenon.
The first half of April will see interspersed rainfall activity. Only when winter rains (Western Disturbances affecting weather) get over, change will take place and per-monsoon rains will occur. This situation is a reflection of poor and weak activity in the Indian seas.
Weather systems developing in April
Weather models at Skymet suggest that two spells of rain can be expected in the Bay of Bengal. The first spell will start appearing in the Bay of Bengal from April 14 and by April 16 the system will cover central parts of the Bay. However, the system will not be strong enough to touch the coastlines.
The second spell will commence on April 21 and affect weather till April 24. However, this system will also reach central Bay and retract thereafter.
Bay of Bengal vs Arabian Sea
The frequency of storms is generally more in Bay of Bengal, in comparison to Arabian Sea. Talking about severity, the storms take almost equal toll on either side. However, due to colder sea surface temperature, most of the storms in the Arabian Sea fizzle out while still over the sea.
History of cyclones in the pre-monsoon season
Last year, only one cyclone developed in the pre-monsoon season, i.e Naunak in the Arabian Sea. Naunak weakened while over the sea and therefore, did not cause any damage in terms of life and property.
Around 50% of the cyclonic disturbances (CDs) that form in the month of April and May intensify in to storms. There is an appreciable increase in the frequency of storms from April to May. In the month of May, most of the storms in the Bay originate between 10˚and 15˚N. They initially move north or northwestward and then recurve in the northeast direction. The entire east coast of India, the coastal parts of Bangladesh and Arakan coast of Myanmar are affected by storms in this month.
In the Arabian Sea, the storms move in the northwest direction towards the coast of Arabia. A few of them move north and later northeast to cross Maharashtra and Gujarat coast.
Picture credit- Munir uz Zaman