First Nada, now Vardah – what's bringing these cyclones to India's east coast?

Just a week after Cyclone Nada made its way across the Bay of Bengal and brought showers to Nagapattinam in coastal Tamil Nadu, a new cyclone called Vardhah is brewing a few hundred km off the coast of the Andaman and Nicobar islands.

The India Meteorological Department has predicted that the storm will gather strength and develop into a severe cyclonic storm on Friday, and sustain itself as such till Monday. It is expected to head towards coastal Andhra Pradesh during which time winds may even touch a speed of 130 kmph. The cyclone is expected to subside considerably by Tuesday.

On December 11 and 12, private forecaster Skymet Weather expects moderate to heavy rain in parts of coastal Andhra Pradesh, with isolated places recording very heavy spells.

‘Don’t panic’

For the past week, the emerging cyclone has brought heavy rain to the Andaman and Nicobar Islands, which thousands of tourists visit at this time of the year. As helicopter and ferry services have been stopped temporarily due to bad weather, many tourists have been unable to return from other islands to Great Andaman, the main archipelago of the Andaman and Nicobar islands, where Port Blair airport is located. Because of this, several tourists have missed their flights home. Poor communication signals have also disrupted communication.

“We have been finding it difficult to contact our team in Havelock,” said a Bangalore-based employee of the Barefoot hotel on Havelock island. “Right now, we are communicating by email. We have heard that all the tourists are safe and we are hoping that the weather clears by tomorrow.”

On Thursday morning, Home Minister Rajnath Singh asked family members of tourists not to panic, as all visitors to the archipelago were safe.

While the local administration has declared this cyclonic storm to be a Level 1 disaster, some residents of Havelock Island are puzzled over the fuss.

When this reporter contacted DIVEIndia – a dive operator on Havelock Island – via Facebook, a representative of the organisation responded by saying that other than the inconvenience of tourists missing their flights, the only other issue was that communication signals were worse than usual.

“This happens two to three times every year,” said the DIVEIndia representative. “Not sure why this year it has become news (maybe because there are more tourists), but it is not materially different from previous times.”

What brings cyclones?

Explaining that India has two cyclonic seasons, the first in the pre-monsoon period of April-June and the second around the time of the North East monsoon from October-December, GP Sharma, former weather chief of the Indian Air Force, said that the low-altitude north easterly winds that herald the North East monsoon also nurture cyclonic depressions in the Bay of Bengal.

“Most of the disturbances that originate in the Bay of Bengal start somewhere around the Andaman sea,” said Sharma.

Sometimes, cyclones also form when remnants of a typhoon travel across the Gulf of Thailand to enter the Bay of Bengal.

“It enters the Bay of Bengal as a weak system,” said Sharma. “But since the Bay of Bengal is a large, open water body, it starts gaining strength here.”

A cyclone needs plenty of water and a surface temperature not less than 26 degrees Celsius to grow and sustain itself. One of the explanations why Cyclone Nada had a short life could be because it entered what is known as a cool pool, an area where the surface temperature was lower than required to sustain the cyclone.

Once, they make landfall, however, cyclones weaken.

“Even if they manage to sustain, make landfall and cross the coast, they will immediately show signs of rapid weakening, because their source of energy gets cut off,” said Sharma.

Cyclonic paths

In October, the cyclones that originate in the Bay of Bengal usually head for Bangladesh and Myanmar, said Sharma. Some of them also hit the coast of West Bengal.

“In November you will find them striking Andhra Pradesh and Orissa,” he said. “They keep moving lower down the coast.”

Tamil Nadu, as well as Andhra Pradesh, are more likely to be hit by cyclones in December, Sharma added.

So what track will Cyclone Vardah take?

“Cyclones are sometimes very mysterious,” said Sharma. “This particular one is still far into the sea. In the last 48 hours itself, it shows it is going to Orissa. At other times it shows that it is recurving. I find that it is yet to stabilise. But for the next 48 hours, we are safe.”