The Bay of Bengal is now hosting tropical cyclone Helen, the second in the basin in a month after the very severe cyclone Phailin scorched Odisha in early October.

‘Helen’ is forecast to grow into a severe cyclone and cross south Andhra Pradesh coast by Thursday night, an India Met Department update said on Wednesday.

SWIFT TRANSFORMATION

The transformation of Tuesday’s depression as a cyclone by next morning was as swift and unanticipated as the previous day when it had intensified twice over in less than 24 hours.

Sea-surface temperatures are at 28 to 29 degree Celsius over west-central Bay of Bengal, just above the threshold for the waters to be able to host and sustain a cyclonic storm.

This compared with the steaming 30 degree Celsius around south-east Bay of Bengal where Helen had originated as a low-pressure area on Monday. The high temperatures sustained there on Wednesday as well.

SEVERE CYCLONE

Helen was located to 470 km east-northeast of Chennai, 430 km east of Kavali and 320 km east-southeast of Machilipatnam on Wednesday afternoon.

The cyclone would further intensify into a severe cyclonic storm by Thursday and cross south Andhra Pradesh coast between Sriharikota and Ongole, close to Kavali by night.

Rain or thundershowers will occur at a few places over Kerala, Tamil Nadu, Puducherry and Lakshadweep by Thursday and increase thereafter.

A weather warning for Wednesday said that heavy to very heavy rainfall with isolated extremely heavy rains will have already lashed south coastal Andhra Pradesh.

HIGH WINDS

A few places over north coastal Andhra Pradesh hit earlier by very severe cyclone Phailin too will have witnessed heavy to very heavy rains.

Winds speed reaching 55-65 km/hr gusting to 75 km/hr will prevail along and off Andhra Pradesh and north Tamil Nadu coast from Wednesday night.

Sea conditions would be rough to very rough along and off Andhra Pradesh coast.

Thursday: Heavy to very heavy rainfall with isolated extremely heavy falls may continue to lash south coastal Andhra Pradesh.

Heavy to very heavy rainfall is likely over north coastal Andhra Pradesh.

FRESH ‘LOW’

Wind speeds will race to gale strength at 100-110 km/hr, gusting to 120 km/hr along and off south Andhra Pradesh and north Tamil Nadu coasts.

Sea conditions would be very high along and off Andhra Pradesh coast.

Friday: Continued heavy to very heavy rainfall with isolated extremely heavy falls for coastal Andhra Pradesh. Heavy to very heavy over Rayalaseema and north Tamil Nadu.

The Met has also retained outlook for a fresh low-pressure developing over south Andaman Sea during next two days. It will go on to intensify further.

>vinson.kurian@thehindu.co.in