A cyclonic circulation has been meandering over South Andaman Sea and Bay Islands for the last 48hr. It has now shifted to Southeast Bay of Bengal (BoB) with a further drift likely over the southern parts of Central BoB. Commensurate with active pre monsoon conditions over the area, an observation watch commenced to monitor and track this weather system. Based on model indications, there was likelihood of formation of a low pressure area over Andaman Sea around this time and possibly grow further to become a significant pre monsoon sea born disturbance.
Statistically and climatologically, it was rather early for a storm to come in this area which normally happens during 2nd half of April and invariably after 3rdweek. Although, environmental conditions including the sea surface temperature are not adverse for cyclogenesis, but amalgamation of all sea and atmospheric based parameters is needed to exploit the heat potential of oceans. As was brought out in the last La Nina article dated 03rdApril, a fortnightly issue of Skymet, Madden Julian Oscillation (MJO) was not placed favorably and therefore, will not support convective activity in the Indian Seas. The ocean based transient equatorial belt of rain and clouds, MJO is still sailing far from the Indian Ocean over Maritime Continent. It is likely to be away from our area of interest till 21st April and is unlikely to assist any storm formation.
The cyclonic circulation over Southeast BoB is unlikely to rev up even to a well marked low pressure area. This broad feature is manifested as scattered convective cloud cluster unlikely to take organized shape. This circulation will retain its identity and keep moving westward across southern parts of Southwest BoB. As such, there is another cyclonic circulation over Sri Lanka and neighborhood up to mid levels of atmosphere. These two features may merge to influence a large area over BoB. Active pre monsoon conditions are expected between 5°N - 10°N and 75°E - 95°E. Fairly widespread rain and thundershower activity accompanied with squall, thunder and lightening is expected over Sri Lanka, South Tamil Nadu and Kerala over the next 3 days. Peak intensity of this spell is likely to be borne by Kerala with heavy thunderstorm and more so for southern half of the state.
