The Northeast monsoon is expected to set in over Tamil Nadu by around the third week of October, starting from October 17. The India Meteorological Department has forecast that the northern parts of Tamil Nadu are likely to receive normal or above-normal rainfall, and the southern parts may receive a normal or deficit rainfall this season.
In its prediction for the Northeast monsoon on Tuesday, the IMD said the seasonal rainfall between October and December in the south peninsular region, including Kerala, Tamil Nadu, and Andhra Pradesh, is expected to be above normal, logging 112% of the long-period average of 33.4 cm.
S. Balachandran, Additional Director General of Meteorology, Chennai, said the State is likely to receive enhanced rainfall during the third and fourth weeks of October, as per the extended rainfall forecast. Normally, the Northeast monsoon sets in around October 20. “The onset of the Northeast monsoon in the third week of October is normal either nine days before or after October 20. Tamil Nadu usually receives an average monsoon rainfall of 44 cm,” he said.
Noting that there are nearly 80% chances for La Nina, one of the significant global weather parameters, to emerge during October and November, he said Tamil Nadu has experienced normal or surplus monsoon rainfall in 69% of the 42 occasions when La Nina had prevailed – going by records spanning between 1940 and 2021.
For instance, the State recorded surplus rainfall during 2010 and 2023. However, it is not the sole factor influencing weather as the State received deficit rainfall in 2016. “We cannot expect the same impact as in the past years owing to changing weather dynamics and other factors such as global warming,” he said.
On the accuracy of weather predictions, he noted that the Department has fine-tuned its forecast and has achieved nearly 85% accuracy in the recent years by increasing observational network and improving weather models.
Earlier, during a virtual press conference, IMD Director General Mrutyunjay Mohapatra, to a question posed by this correspondent, said the southern parts of the State are likely to get a deficit rainfall in October, compared to those in the northern region. During the Northeast monsoon, districts in the central parts would receive a good rainfall. He also noted that there has been an increasing trend in maximum temperature in October during recent years.
Published - October 02, 2024 12:17 am IST
