Climate Change

Bad weather ahead for Bay of Bengal, but how bad will it get?

The flip-flops over a new system brewing to India’s east show that our best climate models are playing catch up with weather systems in a world beset with climate change

 
By Akshit Sangomla
Published: Monday 11 October 2021
A screengrab of a forecast by windy.com on October 11, which shows a low pressure system in the Bay of Bengal
A screengrab of a forecast by windy.com on October 11, which shows a low pressure system in the Bay of Bengal A screengrab of a forecast by windy.com on October 11, which shows a low pressure system in the Bay of Bengal

The looming threat of cyclone formation in the Bay of Bengal in the second week of October and the news around it shows how cyclones in the North Indian Ocean region (includes the Bay of Bengal and the Arabian Sea) are becoming unpredictable.

The India Meteorological Department (IMD) said October 11, 2021 that a low-pressure area may form over the north Andaman Sea October 13.

The IMD, on October 8, had predicted the formation of a low-pressure area in the north Andaman Sea on October 10. It revised its prediction October 9 for the time of formation to the subsequent 48 hours.

The IMD explained in its October 11 cyclone update that the delay in the formation of the low-pressure area was due to the persistence of a cyclonic circulation in the upper layers of the atmosphere, above the north Andaman Sea.

The weather agency predicted that the system may intensify slightly into a well-marked low-pressure area and move in a west-northwestward direction towards the south Odisha and north Andhra coasts. It may reach the coasts on October 15. The update does not say anything about the formation of a cyclone.

The Joint Typhoon Warning Centre of the United States Navy has also not generated any cyclone warning for the North Indian Ocean region as of the evening of October 11.

Some media outlets and weather forecasting companies have been reporting about the formation and even intensification of a cyclone, which would be named Jawad, in the past week.

Odisha-based Sambad news website reported October 6 that two low-pressure areas would be forming over the Bay of Bengal in the second week of October.

The report said one of the low-pressure areas would form October 12 and move towards the Odisha and Andhra Pradesh coasts. The system would cross the coast October 15.

The report did not say anything about further intensification of the system. The report was based on IMD’s North Indian Ocean Extended Range Outlook for Cyclogenesis.

The website published another report October 9 in which it quoted IMD to say that the low-pressure area could intensify into a severe cyclone and move towards the Odisha and Andhra coasts.

The report also quoted Noida-based private forecasting agency, Skymet Weather, to say that the low-pressure area over the north Andaman Sea that would form on October 11, may merge with another low-pressure area that would come from the South China Sea to intensify into a cyclone October 13.

Skymet said the remnant would come from the dissipation of Typhoon Lionrock which hit the Hainan province of southern China October 9.

Skymet had predicted that the storm would make a second landfall along the Vietnam coast and then travel across Laos, Thailand and reach Myanmar.

Here, it might merge with the low-pressure area already present to form a stronger cyclonic circulation. Whether this rare merger happens or not, remains to be seen.

On October 9, the Global Forecasting System (GFS) data, as represented by the website windy.com showed that the system may move very close to the coast between Paradip and Puri in Odisha around the morning of October 17.

A screengrab of a forecast by windy.com on October 9, which shows a cyclonic system in the Bay of BengalA screengrab of a forecast by windy.com on October 9, which shows a cyclonic system in the Bay of Bengal

It may have peak wind speeds of up to 110 km / hr. The GFS data on the same website currently shows that the system would remain a weak low-pressure area around the morning of October 17.

All this shows that our best climate models are only playing catch up with the weather systems in a world beset with climate change.

Even then, cyclones in recent times have been highly unpredictable and sometimes have intensified much more quickly than expected.

Therefore, IMD and other weather agencies will be keeping a close watch on the system that is forming over the north Andaman Sea, its track and intensification. IMD has not generated a cyclone alert for any of the coastal states as yet.

If the cyclone does still form, it would be the third cyclone in the North Indian Ocean region in the past three weeks. Before this, Cyclone Gulab had formed in the Bay of Bengal September 25 and made landfall along the north Andhra coast September 26.

The remnants of the cyclone travelled all the way across India, causing rainfall in Odisha, Chhattisgarh, Maharashtra and Gujarat. It finally dropping back into the Arabian Sea and intensified to form Cyclone Shaheen October 1.

Such an event happened for the first time in the last 40 years. Cyclone Gulab itself had formed from the remnant of a storm in the South China Sea that had crossed over to the Bay of Bengal.

Therefore, a similar event, though unlikely, may happen in the case of the current system as well.

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