New weather system likely in Bay of Bengal; more rain for Tamil Nadu: IMD

According to the Indian Meteorological Department (IMD), a new low-pressure area is likely to form over the Southeast Bay of Bengal by Saturday (Nov 22), and it could intensify over the weekend. As of Monday (Nov. 17), a low-pressure area exists between the south Tamil Nadu and Sri Lanka coasts, which has already been causing rainfall and stormy weather across coastal Tamil Nadu.

In meteorology, alow-pressureareais defined as an area where the atmospheric pressure is lower than that of the surroundingareas. 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 cyclonic storm.

Owing to the existing Low pressure area, an alert for heavy to very heavy rainfall(6-20cms rainfall) has been issued for Chennai city and adjoining districts for Monday, while several other districts have been issued a heavy rainfall warning.

Through the week, heavy rainfall has been predicted for few districts along the Tamil Nadu coast, as a result of the prevalent weather system. By Friday, (Nov 21), heavy rainfall is expected to resume over multiple coastal districts of Tamil Nadu, and this rainfall activity is expected to continue well into the weekend, as the likely low pressure area evolves.

Owing to the gusty winds (speeds of up to 55-60kmph) and rough sea conditions along the Tamil Nadu coast, IMD has advised fishermen not to venture out to sea between November 17and 21. 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.