CHENNAI: Two weather systems are likely over the Bay of Bengal, with a low-pressure area expected to form over the southwest Bay of Bengal within 24 hours and another over the southeast and adjoining east-central Bay of Bengal around October 23.
Meanwhile, the Regional Meteorological Centre (RMC), Chennai, has issued an orange alert for heavy to very heavy rain in several districts, including Chennai, and a yellow alert for heavy rain in other parts of Tamil Nadu on Tuesday (October 20).
An upper-air cyclonic circulation over the Gulf of Thailand and Myanmar is likely to move into the north Andaman Sea by Wednesday morning (October 21), the India Meteorological Department (IMD) said on Tuesday. It is expected to move west-northwestwards, with a low-pressure area likely to form over the southeast and adjoining east-central Bay of Bengal around October 23. The system is likely to move north-northwestwards and intensify further.
Separately, an upper-air cyclonic circulation over the southwest Bay of Bengal off the North Tamil Nadu coast now lies over the southwest Bay of Bengal and adjoining Tamil Nadu coast, the RMC said. Under its influence, a low-pressure area is likely to form over the same region within the next 24 hours.
The RMC also said a trough extends from the circulation over the southwest Bay of Bengal and adjoining Tamil Nadu coast to north coastal Andhra Pradesh.
Heavy rainfall is likely at isolated places in Ranipet, Kancheepuram, Kallakurichi, Tiruchirappalli, Ariyalur, Perambalur, Pudukkottai, Sivagangai, Tenkasi, Tirunelveli and Kanniyakumari districts.
The northeast monsoon has gained momentum across Tamil Nadu, bringing widespread rainfall, particularly to coastal districts, the delta region and areas along the Western Ghats. Chennai witnessed continuous rainfall on Saturday (October 17) night.