Quirky cyclone

Published : Dec 05, 2018 12:30 IST

THE India Meteorological Department (IMD) has recorded that between 1891 and 2017 some 25 cyclonic systems that formed in the Bay of Bengal ended up in the Arabian Sea. Gaja is the 26th system after Cyclone Ochi in 2017 to do so. “In fact, none of the earlier ones caused such severe damage as Gaja did to the livelihood assets of people,” said S. Balachandran, Deputy Director General of the Regional Meteorological Centre of the IMD in Chennai.

Speaking to Frontline , Balachandran said that Gaja was the 14th system to hit the Vedaranyam-Nagapattinam coast in Tamil Nadu in the period from 1891 to 2018 and was the seventh since 1950 to make landfall on the Nagapattinam coast. “These vital statistics show that the coast of Nagapattinam in the delta region is prone to cyclones,” he said.

Balachandran also pointed out that the extent of destruction that a storm system wreaks is closely linked to the socio-economic factors of the land and its people. “Gaja was not an exception,” he said. As the storm did not weaken after the landfall, as was expected, its strong winds and torrential rains left a trail of destruction in the delta region, which is the State’s predominant agricultural zone. Although no cyclonic system can be predicted completely, Gaja’s unpredictability has become the subject of an intense debate among weathermen today.

From November 10, Gaja, which remained an innocuous and distant trough, was playing a game of hide-and-seek with weather predictors. “We had to monitor it closely till November 20, and till it became a weak depression over Theni district in Tamil Nadu before crossing into neighbouring Kerala and entering the Arabian Sea,” he said. In the Bay of Bengal, it had initially moved in a west-north-west direction and then south-westwards, thus making a broad loop. The eye of the cyclone also enlarged to a sprawling 26 km in diameter.

It remained static for nearly 24 hours until 8 a.m. on November 14, keeping its trackers on tenterhooks. Then, it started moving slowly and picked up a speed of 12 km an hour on November 15.

After making landfall, it knifed through the State in a straight line without losing velocity. When it reached Dindigul, an interior district, it maintained a wind speed of 20 to 30 knots (37 to 55.6 km/hr), causing severe damage in the hill station of Kodaikanal. “We constantly monitored the frequent changes in the range of the system and its operational condition as it moved on,” Balachandran said.

The eye of the cyclone was elliptical and turbulent, and hence it took about three to four hours to complete landfall. The system was so powerful that its gusty winds churned the sea violently, causing a huge quantum of marine ooze of slush and mud to be spewed up for a distance of one kilometre on the shore in many villages.

“The sea at that time had withdrawn in Pamban in Ramanathapuram. Like any storm, Gaja had high non-linear interaction with external environment as it moved on. The Met department will now have an exhaustive analytical study on Gaja and its dynamic interactions after assessing the images and readings of radar and satellites,” said Balachandran.

Ilangovan Rajasekaran

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