A cyclonic circulation has formed over Gulf of Martaban, an arm of the Andaman Sea that toys with South Myanmar, which is expected to descend to the lower levels of the atmosphere to set up a low-pressure area, India Meteorological Department (IMD) announced on Thursday.

This will be the first ‘low’ after the onset of monsoon over the Bay of Bengal three days ago. On Thursday, Sri Lanka declared the onset of the monsoon over the island-nation, the penultimate stop ahead of Kerala, at least four days ahead of schedule. Before this, the monsoon had reached Myanmar on May 13 and the Andaman & Nicobar Islands on May 16.

‘Low’ closer to Myanmar

BusinessLine had hinted about the formation of the ‘low’ in that part of the Bay closer to Myanmar than any of the land along the Bay rim. The strong south-westerly flows will force the ‘low’ to uncharastestically cross the Bay, away from India, and land over Indo-China where it is expected to cool its heels.

This could weaken the flows that normally hit the hills in the North-East and turn back towards mainland India. An East-West trough likely being thrown up by a western disturbance from North-West India may stand in instead, and allow cooler south-easterly winds (till then south-westerlies over the Bay) to penetrate the mainland.

Also read
As of May 15, about 405 mills had closed their crushing operations, while 116 sugar mills are still operating in the country

Deals signed to export 85 lakh tonnes of sugar, says ISMA

With storages overflowing, Indonesia to lift palm oil export ban from May 23

Needs proper credentials

Onset of the monsoon over the North-East (just before or after that over Kerala) would need a low-pressure area with proper credentials. It needs to be anchored over the North-West Bay (closer to the East Coast of India) or better still, the Head Bay, to steer the monsoon flows to East and Central India, and later North-West India.

Global models say that the onset over Kerala could happen anytime until May 24 (falls within the larger onset window set by both the IMD and Skymet Weather), but the progress will be secular along the West Coast till at least into June. A larger sweep of the monsoon across the Peninsula and Central India will need support from the Bay in the form of a properly oriented ‘low’ or a depression.

Clouds have covered most parts of the South Peninsula on Thursday morning as a cyclonic circulation persisted over North Tamil Nadu dragging in the flows.

Clouds have covered most parts of the South Peninsula on Thursday morning as a cyclonic circulation persisted over North Tamil Nadu dragging in the flows. | Photo Credit: (nil)

Heavy to very heavy rain

The 24 hours ending Thursday morning saw isolated heavy to very heavy and extremely heavy falls occur over Meghalaya; heavy to very heavy over Coastal and North Interior Karnataka, Kerala, Rayalaseema and Assam; and heavy over the hills of West Bengal, South Interior Karnataka, Tamil Nadu, Arunachal Pradesh, Nagaland, Manipur, Mizoram and Tripura.

A cyclonic circulation over interior Tamil Nadu may weaken after two days, but a rain-spilling trough extending from central Madhya Pradesh into interior Tamil Nadu may outlive it. Arrival of the monsoon will break down both and replace them with a signature off-shore trough along the West Coast during monsoon proper.

Related Topics
comment COMMENT NOW