Southwest monsoon is not the main rainy season for the state of Tamil Nadu. Being a rain shadow area because of Nilgiris on to the west, rainfall is not extensive across the length and breadth of the state. Capital city Chennai has a modest average of 101.7mm and 132.8mm rainfall, during the core monsoon months of July and August. October, November and December in the northeast monsoon season account for nearly 70% of annual rainfall.
State of Tamil Nadu mostly remains out of phase with the countrywide rainfall during the southwest monsoon season. Pan India active monsoon conditions bring a low note and weak monsoon or ‘break monsoon’ spell spike in the rainfall activity. Break monsoon conditions have been prevailing over the country for the last 10 days. Accordingly, there is an uptick in the rainfall for the state. The official observatory at Nungambakkam has recorded 109mm of rainfall during August. Airport observatory at Meenambakkam has crossed the monthly normal of 132.8mm and measured 164.1mm rainfall, just half way through the month.
Fresh low pressure area is likely to form over Bay of Bengal very soon. Partial revival of monsoon is likely over the eastern parts of India. Increase in the monsoon activity over Bay of Bengal and coastal states of Odisha and West Bengal will decelerate the monsoon showers for the state of Tamil Nadu in general and the capital city in particular. Rainfall activity will be very light, patchy and fleeting in nature for the city and suburbs, commencing tomorrow and remaining so till end of the week. After the monsoon low moves inland and later shifts close to the foothills, typical monsoon showers may resume by middle of next week.