Both weather systems in Bay of Bengal to intensify; heavy rain warning for Tamil Nadu

Two weather systems that are simultaneously evolving in different parts of the Bay of Bengal are expected to bring heavy rainfall to regions of Tamil Nadu through this week, according to the Indian Meteorological Department(IMD).

On Tuesday, (25th Nov), IMD announced that a low-pressure area formed between the Tamil Nadu Coast and the Sri Lankan Coast. This system is likely to move north-northwestwards and intensify into a well-marked low-pressure area and further intensify into a depression in the coming days.

The weather system near the Andaman Sea region concentrated into a depression on Tuesday, and it is expected to move west-northwestwards and intensify further during the course of the week.

In meteorology, a low-pressure area is one where the atmospheric pressure is lower than the surrounding areas. It is associated with cloud formation, increased humidity and rainfall. It causes moderate rain, cloudy skies. If multiple factors are favourable, a low-pressure area could gradually intensify in a phased manner into a depression and later into a cyclonic storm.

Rainfall data shared on Tuesday showed that a few locations in Southern Tamil Nadu recorded between 13-17 cm of rainfall over the last 24 hours.

For this week, IMD has issued a heavy-to-very heavy rainfall warning for multiple coastal districts of Tamil Nadu. On Saturday (29th Nov) and Sunday(30th Nov), heavy to very heavy rain has been predicted for Chennai and adjoining districts.

Fishermen have been advised against venturing out to sea through the week, owing to rough conditions and gusty winds. Those engaged in deep-sea fishing have been advised to return ashore.

The formation of multiple weather systems or cyclonic storms in the Bay of Bengal is typical of the ongoing Northeast monsoon season, which is active between mid-October and mid-December. The Northeast monsoon caters for about 50% or more of the annual rainfall in Tamil Nadu and coastal Andhra Pradesh.

This season is known for cyclonic storms or weather systems that form in the Bay of Bengal, which can lead to very heavy rainfall and potential flooding in parts of Tamil Nadu and coastal Andhra Pradesh. These rains are also crucial for recharging the water table and the reservoirs.