Northeast Monsoon onset likely around October 15-16, says IMD

This year, the IMD has predicted ‘above’ normal rainfall and quantitatively 112 per cent of the Long Period Average (1971-2020). Also known as the winter monsoon, the rainfall during October-December is the chief rainy season for Tamil Nadu and also affects Rayalaseema, Yanam, Puducherry, coastal Andhra Pradesh, south interior Karnataka and Kerala.

In its weather update issued on Monday, IMD said, “The Northeast Monsoon rainfall activity is likely to commence over the southeastern peninsular region later this week and simultaneous completion of the withdrawal of the Southwest Monsoon will be realised from remaining parts of the country.”

In the run-up to the onset of the Northeast Monsoon, Tamil Nadu, Puducherry, Karaikal will experience very heavy rain (115-204 mm in 24 hours) till Wednesday with extremely heavy rainfall (more than 204 mm in 24 hours) on October 16, the IMD has warned.

This enhanced rainfall is due to the development of a fresh low-pressure system over the southeast Bay of Bengal on Monday. This system is expected to intensify into a well-marked low-pressure system and move north-westwards across north Tamil Nadu, Puducherry, and southern Andhra Pradesh over the next two days. In addition, there extends a trough from this low-pressure system dipping into the southeast Bay of Bengal.

Due to such favourable weather conditions, there will be no break in the rainfall activity between the two monsoons, particularly over Kerala, Tamil Nadu, Puducherry, and neighbouring areas where heavy rainfall has continued since last week. Heavy rain is forecast over coastal Andhra Pradesh and Yanam on Tuesday and Wednesday, with rainfall activity shifting to Kerala and Mahe on Thursday and Friday.

On Monday, the Southwest Monsoon further retreated from Assam, Meghalaya, Arunachal Pradesh, Nagaland, Manipur, Mizoram, and Tripura and is set to withdraw from the rest of Gujarat, Madhya Pradesh, Chhattisgarh, Odisha, and more parts of Maharashtra over the next two days.

The line of withdrawal of the Southwest Monsoon passed through Gopalpur, Raipur, Khargone, Nandurbar, and Navsari.