Latest analysis show that a low-level circulation persists over Bangladesh and its N-S trough seen upto W-S-W Bay http://ow.ly/i/6YPl4 
Now, GFS model suggests a low-level circulation to pop over S Tamilnadu, Comorin Sea in next 42hrs ... http://ow.ly/i/6YPJa 

During next 2 days the upper-level trough from N Bengal to N Bay is expected to persist ! ... http://ow.ly/i/6YPX6 

Before morning of 24-Sep, and noon,evening of 24-Sep..
Scattered T showers to persist over Tamilnadu, W-ghats kerala http://ow.ly/i/6YQ99 
24-Sep...
T showers for S,W,central Karnataka, W-ghats Karnataka and into S,S-W Maharastra.
#Chennai - Tomorrow again...
T showers expected for N-W,W,S-W suburbs and less rain forecast for city.
Scattered T showers for N-E Tamilnadu

Scattered HEAVY T showers will continue over N Bengal, Bangladesh and central, S zones of N-E states.

#Chennai - 4:10pm, having a HOT and Humid day!
Heavy T showers sweeping over W,W-S-W at 65 to 90km from city ... http://ow.ly/i/6YJba 
#Chennai - T showers seen over W,W-S-W is traveling South.
But before 10pm a T shower may pop over N-W,W,S-W suburbs of city !

3:30pm, Most of India is DRY.
Showers seen over central,S zones of N-E states ... http://ow.ly/i/6YJib 
3:30pm, T showers popping over S Odisha, S chatisgarh, N-E,S Andhra, S-central Tamilnadu ... http://ow.ly/i/6YJib