Pune: Days after Cyclone Arnab struck the Andhra Pradesh coast, a fresh weather system is likely to develop over the Bay of Bengal, IMD said on Saturday. It may lead to rainfall in parts of Maharashtra over the next few days.The system, which originated as a low-pressure area over the South Andaman Sea on Oct 29, has moved west-northwestwards and intensified into a depression over the southeast Bay of Bengal.For Maharashtra, the evolving track of the system will be crucial. IMD officials said it was too early to assess its impact on the state as the system’s movement and track were yet to become clearer. “Another two days are needed for the track to become clearer. Any possible impact on Maharashtra would be in terms of rainfall. The system is expected to lose considerable intensity by the time it moves inland,” an IMD official said.As of late Saturday, the depression lay about 960km southeast of Chennai, 980km southeast of Visakhapatnam, 1,030km southeast of Machilipatnam, and 1,080km southeast of Ongole.In its latest press release issued on Saturday evening, the IMD said the depression was very likely to intensify into a deep depression over the southeast Bay of Bengal within the next 12 hours. It is then expected to strengthen into a severe cyclonic storm, with wind speeds of 100-110kmph, gusting up to 120kmph. The system is likely to reach the west-central Bay of Bengal by Nov 2 and approach the Andhra Pradesh coast between Nellore and Narsapur by the early hours of Nov 3.In an earlier bulletin issued on Oct 31, the weather department issued a pre-cyclone watch (yellow message) for the Andhra Pradesh coast. The IMD will provide a more precise location, timing, and advisory as and when fresh assessments are issued.IMD director-general Mrutyunjay Mohapatra told TOI that the system is expected to cross the south Andhra Pradesh coast on Nov 3. He added that the exact landfall location could not yet be determined, as the system was still several days away from the coast. The most likely track currently indicates landfall along southern Andhra Pradesh.Mohapatra said the system will be named Murasu once it is classified as a cyclonic storm, making it the second cyclone of the year after Arnab.“Rainfall activity over Andhra Pradesh is likely to be higher on Nov 2 and 3. South Odisha is expected to receive heavy to very heavy rainfall on Nov 3 and 4. Very heavy rainfall could reach 200-300mm at some places in these regions,” Mohapatra told TOI.He said the system is forecast to have wind speeds of 100-110kmph, gusting up to 120kmph. Arnab had made landfall with wind speeds of around 150kmph, he added.Explaining the unusual sequence of two cyclones developing in quick succession, Mohapatra told TOI, “The Madden-Julian Oscillation is very active and in phase 3. It is near the Bay of Bengal and is helping the genesis of two cyclones one after the other. Along with the MJO, the equatorial Rossby wave is also favourable. When these waves work together over the same area, cyclogenesis becomes favourable.”Mohapatra said India usually records four to five cyclones annually, with three to four typically developing during the Oct-Dec post-monsoon season and one to two during the pre-monsoon period (April-June). However, there were no cyclones during either the pre-monsoon or monsoon season this year. Arnab was the first, and the new system would be the second.He attributed the below-normal cyclone activity so far partly to the prevailing strong El Nino conditions. “During El Nino years, the number of cyclones over the Bay of Bengal and Arabian Sea generally tends to be below normal and affects the Tamil Nadu and Andhra Pradesh coasts. Storms also tend to be less intense and have shorter tracks and life cycles,” he said.“In La Nina years, however, cyclone tracks are more likely to extend towards Odisha, West Bengal, Bangladesh and Myanmar,” Mohapatra added.On long-term trends and climate change, Mohapatra said the overall number of cyclones is declining, but the number of intense cyclones is either remaining the same or increasing.He also highlighted the growing concern over extremely severe cyclones slowing down as they approach India’s east coast. “The recent Cyclone Arnab is the best example. We saw how it took six hours to complete the landfall process over Andhra Pradesh. When a cyclone moves slowly, the landfall process becomes longer and the impact of wind and rainfall can be greater,” he said.
