KOCHI: Though the scientists at India Meteorological Department(IMD) and National Centre for Earth Science Studies(NCESS) had issued a forecast for Cyclone Ockhi, which originated over the Bay of Bengal on November 29, the super storm surprised them by picking up pace overnight and heading towards the Arabian Sea. According to the scientists this has been the most intense cyclone to traverse the Arabian sea after Cyclone Megh which battered the Oman coast in 2015.
While the meteorologists were expecting the storm to take a deflection towards the left and move towards eastern coast, it started whirling in an anticlockwise direction and started moving towards the Arabian Sea. “This is the first time in the last 70 years a cyclone of such intensity had pummelled the Kerala coastal belt. Though it did not make a landfall, the sea was quite choppy. Though the IMD had issued a warning on November 29, at the time of issuing the warning there was no indication of it developing into a super storm and moving to the Arabian Sea.
It was not a forecast failure but the lack of lead time. The storm gathered pace and moved towards the Thiruvananthapuram coast on November 30 and we got only a day's lead time. By the time we issued the warning several fishermen had already ventured out into the sea. This element of surprise heightened the disaster's intensity,” said IMD director S Sudevan.
Though cyclonic storms lash the east coast regularly, the Arabian sea had been relatively safe. Had this notion of a safe zone lead to a sense of complacency and affect the state's preparedness in disaster management? Scientists said the cyclone would not have proved devastating had they got one more day's lead time. As Lakshadweep and Kozhikode got an additional day, the fishermen were warned in time, said a senior scientist.
“The warm moist air over the ocean rises upward causing a low-pressure on the ocean surface. Air from surrounding areas rush to the low- pressure area creating an ideal atmosphere for cyclones to take birth.The moist air and wind spin at high velocity and the water evaporating from the ocean gets sucked in. High-pressure air from above flows into the vortex and the system starts rotating at high speed. It is the warm and moist air which acts as fuel and decide the course of the storm,” said a scientist.
“The conditions in the Bay of Bengal are ideal for cyclonic storms,” said NCESS' Atmospheric Processes group head K K Ramachandran.
“For cyclones, there should be more moisture content in the air and as water in the Bay of Bengal is less saline there is more moisture in the air. The temperature is also a deciding factor. This year in the post-monsoon period these factors created an ideal atmosphere and changed the trajectory of the cyclone,” he said.
“Normally the sea level rises during the December–January period and there will be less gravity. This year the sea level had risen by 12 cm. It coincided with many factors. Usually such phenomenon does not occur during fair weather. It was an unusual situation,” said Ramachandran.The wind speed which was 55 km on November 29 had gone up twice to 110 km on November 30 and was barely believable, according to a scientist.
Though the cyclone made the sea rough it was not devastating when it struck Lakshadweep. Except for Minicoy, the impact was not disastrous. This was due to the peculiarity of the coastal area in Lakshadweep. The sea is deep in the eastern coast of Lakshadweep while there are lagoons on western side. This reduced the impact of the cyclone, he said.