TNM fact-check: Two more cyclonic systems brewing in Bay of Bengal claims viral message

A WhatsApp forward claims another cyclone called Burevi is brewing in the Bay of Bengal and could bring more rains for Chennai.
Waterlogging in Chennai due to Cyclone Nivar
Waterlogging in Chennai due to Cyclone Nivar
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Cyclone Nivar, categorised as a very severe cyclonic storm, made landfall near Puducherry between 11.30 pm on Wednesday to 2.30 am on Thursday. Wind speeds touched 120-130kmph, said the India Meteorological Department (IMD), when Cyclone Nivar crossed the coasts of Puducherry and Tamil Nadu. The system has since weakened into a severe cyclonic storm and as it makes its way over land, Nivar will weaken further into a cyclonic storm over the next six hours, stated IMD. 

A WhatsApp message that is doing the rounds, however, claimed, “Nivar crossed as an empty shell (the centre collapsed before the landfall) near Pondy and is now making its way over land. In spite of the weakening, we can still feel the gusts in Chennai and you can imagine the power of this cyclone. I would call it divine intervention that it weakened. Else the damage would have been catastrophic.”

“We will continue to feel these gusts until afternoon. No big rains expected, but Nivar has been a surprise for all of us. Light to moderate rains may continue until tomorrow. But the rains are not over for Chennai. 2 more systems are lining up in the Bay of Bengal out of which 1 could become another cyclone called Burevi. The next system is expected to be hit our coasts by 1st or 2nd and the the next by 10th or 11th Dec (sic),” said the WhatsApp message. 

TNM spoke to weather blogger K Srikanth, who runs Chennai Rains handle on Twitter, to fact-check the WhatsApp forward. “No, I would not say it crossed as an empty shell. But yesterday, in a series of tweets I mentioned the possibility that the system got sheared (change in wind speed or direction). The system did get sheared to the west. So that impact could have meant the system did not make landfall as intensely as it was expected. I would not call it an empty shell,” he explained. 

Early pictures from different parts of Tamil Nadu and Puducherry showed inundation and waterlogging in several areas owing to heavy rains brought by Cyclone Nivar. Pradeep John, another weather blogger from Chennai, pointed out that Cyclone Nivar was different from Cyclone Vardah in 2016 and Cyclone Gaja in 2018, with rains causing damage, as opposed to strong winds.  

Explaining why Cyclone Nivar brought in more rains, Srikanth said that the system did not travel long, having developed over north Sri Lanka. “In a sheared system, there is a tendency to have rains as well. It did not form in the Andamans. Systems which travel much longer, tend to become stronger in terms of wind and more compact as well. So it has a lot of time to consolidate, and becomes more compact as a cyclone. Cyclone Nivar travelled from nearer to north Sri Lanka. Since it travelled in a south-easterly direction, it could have some land interaction much earlier. So, that would mean there could be more rainfall than wind.”  

As per IMD, Puducherry received 303.5 mm of rainfall between 8.30 am on Wednesday and 8.30 am on Thursday. Villupuram recorded 140.3 mm of rainfall during the 24-hour window, followed by Chennai (138.5) and Chengalpattu (124.8). In fact, as pointed out by Pradeep John in his blog post, Chennai has received its entire share of rainfall (801.3 mm) so far for the Northeast monsoon season. With another month to go before the Northeast monsoon withdraws, Chennai could well see an excess at the end of the season. 

Both Srikanth and Pradeep note that rains may continue in Chennai over the next few days. Srikanth in his YouTube video explained that gusty conditions will continue in north Tamil Nadu over the next few hours on Thursday owing to the influence of the cyclone.  

Cyclone Burevi next?

S Balachandran , the Deputy Director General of Meteorology Chennai, told TNM that a low pressure area is likely to form around November 29. However, whether it will intensify into a cyclone is yet to be known. “Right now a low pressure area is likely to form around November 29. It is likely to move westwards towards south Tamil Nadu. We can predict even 15 days-20 days before but accuracy won’t be there. So whether iit will go into intensification of cyclone is yet to be known,” he said.

As far as two more systems are concerned, Srikanth told TNM, “There is possibly a second one. But it’s too early to say. The first one we can talk of only in terms of a system and not in terms of where and all that.”  

The first system that he refers to is the one forming off the Sumatra coast near the Andaman islands and which could bring rain to the coast of Tamil Nadu in early December. However, contrary to the WhatsApp message, Srikanth said that it is unlikely to develop into a cyclone. “I personally feel, the system won’t be a cyclone as it has to travel over the same waters of Nivar. That means, the water could be slightly cooler after Cyclone Nivar formed. So we may have depression or something like that. But it could mean it could go to Delta rather than north Tamil Nadu.” 

Meanwhile, the source of the WhatsApp forward over the two cyclonic systems appears to be based on a tweet by a meteorologist with AccuWeather, a US-based weather forecasting agency. 

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