This cyclone season’s first ever weather system would form over north Andaman Sea around October 10 and it does not augur well for Dussehra and post-puja period, if one goes by preliminary forecast based on models. The system, India Meteorological Department (IMD) on Wednesday, October 6, 2021, said, is likely to become more marked and move west-northwestwards towards south Odisha and north coastal Andhra Pradesh coast in subsequent four to five days.
The existing restrictions for Durga Puja to contain the spread of Covid-19 have dampened the festive mood and the rains could add more water to it.“We are closely monitoring the system. Its precise track can be ascertained after the low pressure is formed,” said Scientist of Bhubaneswar Meteorological Centre Umasankar Das. Some of the global models are looking at a storm of intensity around the October 14-18 period. The potential genesis of the low-pressure area around north Andaman Sea strengthens the projection that the system might gather power.
However, key parameters such as sea surface temperature and vertical wind shear would be decisive. Besides, there are projections for a number of extreme weather event activities during the same period which will have bearing on the north Indian Ocean zone. October, however, has a history of bearing cyclones that have battered the eastern coast, particularly Odisha. At least five low-pressure systems have intensified into cyclonic storms over the Bay of Bengal in the month of October in the last 22 years.
The 1999 Super Cyclone that ravaged the State made landfall on October 29. In 2012, severe cyclone Nilam crossed near Mahabalipuram on October 31. Phailin, an extremely severe cyclonic storm landed near Gopalpur on October 12, 2013, while a similarly extreme severe cyclone Hudhud hit Visakhapatnam on October 12, 2014. Four years later in 2018, Titli, a very severe cyclone crossed the coast near Gopalpur on October 11, 2018.
This year, as many as 10 low-pressure areas formed over the Bay of Bengal (BoB) between June and September and this is the first over BOB in the post-monsoon season. Climatologically, the Bay of Bengal and Arabian Sea experience five cyclones annually – one over the Arabian Sea and four over the Bay of Bengal. Considering the seasonal frequency, primary maxima of frequency of cyclones occur during April-June and secondary maxima during October-December. Of five cyclones, one develops during pre-monsoon season and four during post-monsoon season.
Weather experts point out that the formation of a low-pressure area and subsequent intensification into a cyclonic storm depends on the temperature of the sea surface. Another contributing factor is wind shear which is the difference in wind speed or direction over a relatively short distance in two atmospheric levels. When the difference is less, it helps the cyclonic storm gain strength.