An India Met Department (IMD) update has confirmed that the anticipated depression has formed over South-East Bay of Bengal, 1,160 km south-east of Machilipatnam (Andhra Pradesh) and 1,250 km south-south-east of Gopalpur (Odisha).
It is forecast to move north-west and intensify into a deep depression and reach the Andhra Pradesh coast by Friday evening. The IMD said there is a possibility of a slight weakening when it reaches the Andhra Pradesh coast.
DISRUPTING INFLUENCE
Earlier, global forecasts had said the depression in the South-East Bay had already come under the disrupting influence of the 'killer' western disturbance that had accounted for the once-powerful Arabian Sea cyclone 'Ockhi.'
Satellite pictures at noon showed flanks of the Bay system to its west, north and north-east exposed by the marauding westerly winds from the invader disturbance and its offspring circulation.
The system presented as an elongated mass (rather than circular) of convective clouds due to the influence of the westerly winds. The convection to its East and North are being sheared off, unsettling the structure.
This is despite the moderate to good sea-surface temperatures (28- to 29 deg Celsius) and some 'window effect' to the top that allows the building depression to breath in and out.
MARGINAL ENVIRONMENT
Overall, the system is constrained by a marginal environment and limited development due mainly to the moderate to high vertical wind shear value of 37 km/hr to 55 km/hr.
Vertical wind shear refers to the change in speed and direction of winds with height. High shear values chop the head of the storm tower that rises 10-12 km in the case of a full-fledged cyclone.
Satellite pictures also showed clouds being blown away from the Central Bay of Bengal to the Bengal, Bangladesh and Myanmar coasts.
A warning with respect to squally winds and rough seas are currently valid for the Andaman & Nicobar Islands, while fishermen from both the islands and the Tamil Nadu coast on the mainland have been advised caution.
Meanwhile, the remnant of erstwhile cyclone 'Ockhi' lay as a low-pressure area over South Coastal Gujarat. It could emerge back in the North-Arabian Sea, move West, and fade out in the seas.