During the last 24 hours, the Nungambakkam observatory of Chennai recorded 19 mm and Minambakkam recorded 25 mm of rain. Many other parts of the city recorded much heavier rain leading to waterlogging at many places. Chrompet area of Chennai witnessed flash floods leading to traffic jams.
A cyclonic circulation is over southwest and the adjoining west Central Bay of Bengal which is responsible for these intense showers over Chennai and suburbs. In fact, many parts of Tamil Nadu recorded heavy rainfall such as Karaikal, Nagapattinam, Dharmapuri, Atiramapattinam, and Ariyalur.
Now, we expect moderate to heavy rains over Chennai, Puducherry, many parts of Tamil Nadu such as Thiruvallur, Kanchipuram, Chengalpattu, Tiruvannamalai and Cuddalore.
The cyclonic circulation is expected to move over coastal Andhra Pradesh in the next 24 hours. Therefore, rain activities will start reducing from tomorrow. Tamil Nadu is in the rain shadow area therefore Tamil Nadu as well as Chennai do not receive good rainfall during Southwest Monsoon. Normal for Chennai between June 1 and July 28 is just 163.5 mm and Chennai has already received 160.4 mm rain. Therefore, it is just 2% rain deficient.