The Indian Ocean Dipole (IOD) remained positive all throughout the Monsoon season, magnifying the frequency of low pressure areas and cyclonic circulations mainly over the Bay of Bengal during the past two months.
According to SkyMetWeather, a number of cyclonic circulations were recorded over Tamil Nadu and Andhra Pradesh coast in the past three to four weeks.
The circulations sometimes enhanced into low pressure areas, bringing rain over Chennai.
Light to moderate and occasionally heavy rains was recorded over Chennai in the last three weeks. Reports also confirmed that September 18 was Chennai's wettest day in 2019, with 104 mm (4 inches) of rain. The last time the city recorded 100 mm (3.9 inches) of rain within a 24-hour period was in August 2011.
West of Thirumazhisai.TS approaching chennai.— Rainman (@MASRain91) September 21, 2019
Pic courtesy. Chandramouli pic.twitter.com/VDYDYT3Ufw
So far, the city has received 17 400 million liters (4 496 million gallons) of water which can provide the city's water supply for 21 days.
Chennai is located in a rain shadow area and usually gets less rainfall during this period.
Featured image credit: Rainman, Chandramouli