Bay of Bengal Tropical Cyclone Mahasen is in for a long haul as it lurked 1,230 km south-east of Chennai and 1,650 km south-west of Chittagong, Bangladesh, on Saturday afternoon. Tracker models give the enormous storm, whose wing span covers the whole Bay, a free run of the warm waters of the basin for at least the next four to five days.
Warm seas fuel convection and feed the storm with moisture. ‘Ventilation’ at the top of the storm tower (rising kilometres high) allows it to ‘breathe’ and sustain itself. Mahasen underwent intensification at a frenetic pace even as it moved laterally across waters in a west-northwest direction from where it had lain as a low-pressure area a day ago.
The storm is forecast to intensify as a severe cyclonic storm and even further as a very severe cyclonic storm by Monday. It would continue to advance closer to Andhra Pradesh-Odisha coast until it gets stopped mid-sea by a western disturbance moving across North-west and East India.
Mahasen would be forced to re-curve, turning almost 90 degrees to east-northeast and head towards the Bangladesh-Myanmar coast. It would spare the Indian coast from a direct hit, but is expected to set up high winds and moderate to heavy rain along the coasts of Andhra Pradesh and Odisha; eastern parts of Chhattisgarh and Bihar; entire Jharkhand, Gangetic West Bengal and the North-Eastern States.
In fact, Mahasen would miss Kolkata by a whisker as it barrels its way to the South of the metropolis and storm into Bangladesh and Myanmar.
A couple of models even suggested Chittagong as a likely target, in which case Kolkata, Gangetic West Bengal and the adjoining North-East also could face the storm’s fury.
Another model went to the extent of projecting that Mahasen would scythe through the Sunderbans and into West Bengal proper. But all these projections would have to wait until Mahasen comes under the influence of the western disturbance and the virility with which it launches itself on the home stretch. This is expected to take until Wednesday or early Thursday, allowing disaster managers to take stock of the situation and assess its damaging impact across the region.