The normal date of Northeast Monsoon to arrive over Southern Peninsula including Chennai is October 20 and the city of Chennai will soon get the taste of Northeast Monsoon. However, before that, on and off light to moderate rains are expected to be seen over Chennai.
A cyclonic circulation is over North Andaman Sea and a low-pressure area may develop over same region by tomorrow under the influence of the circulation. A cyclonic circulation is also over East Central Arabian Sea.
The upcoming low will not shift inside deep inside the land, and will shift along the coast southward. Because of the withdrawal, dry air mass does not allow the moist winds from the coast as well.
Thus, the system will come close to Tamil Nadu and Andhra Coast and the Cyclonic Circulation from Arabian Sea will also shift towards Kerala and Interior Tamil Nadu. Therefore, varied intensity rains for the next 3-4 days and some weather change will be seen.
In fact, rains will be moderate today, light tomorrow and will remain between light for next 3 days. By the time the system shifts, after about 3 days or so, rains in Chennai may become moderate in nature but heavy showers will remain far away from the city of Chennai.