October storm in Bay of Bengal after 3 years: When, where it is likely to hit

“After the withdrawal of the Southwest monsoon, there is a rise in ocean heating, which leads to rise in sea surface temperature over the Bay of Bengal. The atmospheric moisture availability over the ocean region, too, is higher. So, when remnant systems from the South China Sea reach the Bay of Bengal, they get conducive conditions, aiding the formation and intensification of cyclones in October,” said Umasankar Das, IMD scientist from Meteorological Centre, Bhubaneshwar.

In some years, ocean-atmospheric factors hinder this phenomenon. For instance, in 2020, weak La Nina conditions along the equatorial Pacific Ocean prevented a cyclonic formation near India’s coasts.

Cyclone Sitrang

On Thursday, IMD officials said the cyclonic storm set to develop in east-central Bay of Bengal on October 24 will reach close to the coasts of West Bengal – Bangladesh by October 25.

The name Sitrang (read Si-trang) has been given by Thailand, and features in the list of tropical cyclone names prepared by the RMSC being followed since April 2020. The IMD is one of the world’s six RMSCs mandated to provide cyclone advisories and alerts to 13 member countries — Bangladesh, India, Iran, Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, United Arab Emirates and Yemen.

Which states are likely to be affected ?

The IMD is yet to release the probable cyclone track, but as per the latest updates, the prevailing low pressure system will strengthen and move towards India’s east coast in the coming four days. Gale winds and enhanced rainfall are expected mainly over Andaman and Nicobar islands, Odisha, West Bengal and Bangladesh, particularly the coastal districts.

Weather models as on Thursday suggested that the low pressure system (wind speed of 31 km/hr) will strengthen into a depression (wind speed of 31 to 50km/hr) by October 22 and further into a deep depression (wind speed of 51-61km/hr) by October 23.

Thereafter, it will most likely re-curve northeastwards, thus skirting past the Odisha coast. As it progresses, it will intensify into a cyclonic storm (windspeed of 62 – 87kms/hr) by October 25. The storm is expected to reach close to the West Bengal and Bangladesh coasts in the north Bay of Bengal on October 25.

Winds with speed ranging between 40-45 km/hr gusting to 55 km/hr are likely over the Andaman Sea and Andaman and Nicobar islands on Friday. Here, light to moderate rainfall (15.6 to 64.4mm in 24 hours) will continue till Saturday.

As the storm is expected to come close to Odisha shores, heavy to very heavy rain (64.5 to 204.4mm in 24 hour) would lash over Puri, Jagatsinghpur and Kendraparha districts during October 22-25. The IMD has issued a ‘yellow’ for these coastal districts. Districts along the Gangetic West Bengal, too, will experience moderate rainfall accompanied by lightning on October 24 and 25.

Once the cyclone develops, heavy rainfall is likely to lash Mayurbhanj, Baleshwar, Bhadrak, Jajpur, Cuttack, Khorda, Nayagarh, Puri, Kendraparha and Jagatsinghpur districts on October 24 and all these districts are on ‘yellow’ alert.

Cyclones in the Arabian Sea

In comparison with the Bay of Bengal, only 32 storms have developed in the Arabian Sea in October since 1891. Climatologically too, the IMD states that of the five storms formed in the North Indian Ocean in a calendar year, four are in the Bay of Bengal and one in Arabian Sea.