CHENNAI: The Northeast monsoon is likely to commence over Tamil Nadu between October 15 and 21, with the southern and southwestern regions and adjoining coastal areas expected to receive normal to above-normal rainfall, India Meteorological Department (IMD) director Mrutyunjay Mohapatra said on Thursday (October 1).

Speaking to reporters on the sidelines of a seminar on the seasonal forecast for the Northeast monsoon held at the National Institute of Ocean Technology (NIOT) in Pallikaranai, Mohapatra said heatwave forecasts were being issued with an accuracy of 88%.

The accuracy in predicting the location and time of cyclone landfall had reached a level of zero error. This had helped reduce deaths during cyclones from thousands to almost zero, he noted.

The infrastructure for weather forecasting is also being strengthened in southern states, including Tamil Nadu and Puducherry. Four new radars are to be installed in Tamil Nadu, Mohapatra said.

He elaborated that the IMD would provide technical assistance for automatic weather stations and rain gauges to be installed by the State government.

Using these data, accurate weather forecasts and hazard assessments would be provided at panchayat, taluk and village levels.

Mohapatra said that with an increase in the quality and quantity of data, weather forecast accuracy was expected to improve by another 10% over the next two to three years.

On El Nino, he said it was currently in a strong phase and was expected to remain strong or very strong during the Northeast monsoon period, which would continue until December.

Its intensity was expected to decline thereafter.

He said El Nino generally did not have a major negative impact on Northeast monsoon rainfall. However, the relationship between El Nino and rainfall had changed over time.

In an El Niño year, the number of cyclones formed is likely to be lower, while their intensity, lifespan and travel distance are also expected to be lower.

Cyclones could form over the southern Bay of Bengal or southeastern Bay of Bengal and move in a west northwest direction.

This could increase the possibility of cyclones moving towards the coastal areas of Tamil Nadu, Puducherry, southern Andhra Pradesh and Sri Lanka.

Tamil Nadu Revenue and Disaster Management Department Commissioner Chandramohan and weather scientists also participated in the seminar.

Chandramohan said the State government had conducted detailed review meetings chaired by Chief Minister C Joseph Vijay to prepare for the monsoon.

Waterlogging prone locations across Tamil Nadu had been identified and categorised based on the extent of water accumulation, such as high and very high.

"We have created an Integrated Flood Warning System. It will provide advance information about possible flooding and identify the locations likely to be affected three days in advance, enabling authorities to take precautionary measures. For now, this system has been established in Chennai city," he said.

Chandramohan said rain gauges were currently available at around 1,400 locations across the State.

An additional 1,000 rain gauges would be installed to enable authorities to easily assess the amount of rainfall received in different locations.