The depression-in-the-making in the South-East Bay of Bengal has already come under the disrupting influence of the 'killer' western disturbance that accounted for the once-powerful Arabian Sea cyclone 'Ockhi.'
Satellite pictures at noon show flanks of the Bay system to its west, north and north-east compromised by the marauding westerly winds from the invader disturbance and its offspring circulation.
ELONGATED CLOUD MASS
The system presented itself 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 breath out.
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.
The prevailing western disturbance is contributing to most of the shear, with a barrage of westerly winds blowing hard into the building depression, located by US Joint Typhoon Warning Centre at 1208 km south-east of Visakhapatnam.
CLOUDS SHEARED AWAY
Satellite pictures at noon showed clouds being sheared away in this manner from Central Bay of Bengal to the Bengal, Bangladesh and Myanmar coasts.
Earlier this morning, the India Met Department (IMD) said a persisting well-marked low-pressure area over the South-East Bay of Bengal was expected to become a depression over a period of the following six hours.
Confirmation with regard to the latest status is awaited, even as the IMD said it expected the system to become a deep depression by Friday.
But the way angry westerlies are blowing into the Bay of Bengal from this morning, it remains to be seen at what pace the projected intensification can materialise.
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.