The depression that sprung up early this morning over West-Central Bay of Bengal moved northwards in and lay 440 km south of Chandbali and 340 km south-southeast of Puri in Odisha at 8.30 am.

The system is expected to move north-northwestwards (orienting itself towards the coast) and cross the the Odisha between Chandbali and Puri by midnight tonight or early tomorrow morning.

The depression may undergo a round of intensification into a deep depression a few hours before it crosses coast, India Met Department (IMD) said in its noon update.

Interestingly, a weather tracker of the US Climate Prediction Centre has alluded to follow-up activity in the East-Central Bay of Bengal after the current depression/deep depression crosses land.

This is expected to roll out between October 23 and 28, with a likely bearing on the onset of North-East monsoon over the South-East coast and its progress.

The IMD said that, in between, from around May 25, winds over South Peninsula would turn north-easterly to easterly, preparing the ground for the arrival of the North-East monsoon. It would take a couple of days more for the flows to organise over the entire stretch of Bay of Bengal, though pilot rains are expected to lash the Tamil Nadu coast after October 26.

The European Centre for Medium-Range Weather Forecasts sees helpful troughs falling in place over South-West Bay of Bengal and South-East Arabian Sea to welcome the North-East monsoon.

The US Climate Prediction Centre signals scope for fresh and widespread rains over South Peninsula during October 25 to 31, indicating arrival of the seasonal rains.

Pacific conundrum

The busying waters of the North-West Pacific/South China Sea with three cyclone/typhoon alerts were thought to be exerting drag on the well-marked 'low' in the Bay than earlier thought.

Of these, typhoon Lan is already picking momentum as it races to the north from east of the Philippines. A new tropical depression from South China Sea is now heading into the Central Philippines.

Both these storms are away-going from the perspective of the well-marked 'low' in the Bay of Bengal, which, being in almost similar latitudes, was being made to share 'resources' available.

The 'resources' pertained mainly to the south-westerly flows that feed into the system and the moisture feed they carry, which is the fuel that the storms require to strengthen.

A good amount of the flows directed from the South Arabian Sea and to the south of Sri Lanka and further into the South Bay of Bengal was getting diverted in this manner into the North-West Pacific.

Split model guidance

The US Joint Typhoon Warning Centre had said in its update midnight last night that the Bay system was located 900 km to the south of Kolkata.

It had entered a supportive environment marked by marked by low vertical wind shear, better 'window' effect to the top, and higher sea surface temperatures to the north of the East Coast.

Low vertical wind shear helps the system to retain its structure, 'window' on top allows it to breathe better and higher sea surface temperatures gives it the fuel (moisture) in order to grow.

But the US agency said global models were split as to the degree of intensification and organisation of the system, with some not predicting it reaching even depression strength.

Importantly, the agency had added that the system may track northwestward to northward 'over the next several days' which went to rule out a landfall that IMD has predicted for this evening.

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