99W is now an elongated circulation over N-E to S-W Srilanka... http://ow.ly/i/7yKe3 
In next 24hrs, 99W is expected to cross into Gulf Mannar, S tip Tamilnadu and push into S-E Arabian sea as trough.. http://ow.ly/i/7yKky 

The easterlies along Tamilnadu coast will peak on Thursday.
HEAVY rain ahead.
From early hrs of 13-Nov...
More HEAVY widespread rain for Chennai, N,central,S-E coast of Tamilnadu, S coast Andhra http://ow.ly/i/7yL1h 
For N-coast Tamilnadu, Chennai... Heavy rain forecast for most of Thursday and into morning of Friday.

Noon, evening, late-evening of 13-Nov...
HEAVY T showers for many zones of interior Tamilnadu and over S,S-W,W-ghats of Tamilnadu.
13-Nov, Due to easterly trough along kerala, karnataka coast.
T showers for N,central,S Kerala, W-ghats Karnataka into W-ghats Maharastra
Scattered HEAVY T shower alert for S,S-W Tamilnadu on evening of 13-Nov.

Weather Instagram at November 12, 2014 at 06:59PM

6:50pm, No signs of stopping in Karaikal ! In Chennai too ! #weather

from Instagram

Weather Instagram at November 12, 2014 at 06:00PM

Karaikal - 5:45pm, Heavy rain ! #weather

from Instagram

#Chennai - 6pm, light Showers started... going to be widespread, moderate to heavy and "will last till 12am" !! ... http://ow.ly/i/7ysIc 

Weather Instagram at November 12, 2014 at 05:25PM

Chennai - 5:15pm, mount road photo. Dark now and drizzle over Polichalur zone. #weather

from Instagram

Karaikal - 5:07pm, Massive thunderstorm here.

99W as a LOW is crossing into E-N-E Srilanka now ... http://ow.ly/i/7yphi 
99W is expected to push across Gulf Mannar, S tip Tamilnadu and into S-E corner Arabian sea in next 36hrs.

3:30pm, More HEAVY rain expected to push into coastal Tamilnadu in next 4hrs as 99W is moving West... http://ow.ly/i/7ypoK 

@sarakumar1 >> Chennai - 4:30pm, a long steady, moderate shower system is expected to push into city from E-S-E in next 30 min.
#Chennai, N-coast Tamilnadu is in for a long spell of moderate rain starting in next 30 min.. can persist till 9pm ! http://ow.ly/i/7ypwQ 

Weather Instagram at November 12, 2014 at 03:30PM

#chennai - 2:50pm, Anakaputhur zone.. Drizzle. #weather

from Instagram

@archvivekh .. 99W as a Low is now near ENE srilanka coast. It'll push into Gulf Mannar in 18 hrs. Heavy rain ahead for TN coast, interiors.

7am, Heavy rain with wind here at Karaikal.

Weather Instagram at November 12, 2014 at 06:32AM

Chennai - 5:35am, heavy rain continue and more to come before 12pm. Photo from Madhavaram. #weather

from Instagram

Intermittent light to moderate rains in Chennai

 [1] The movement of the system is in N-NWly direction.

[2] The lower level NEly is touching Chennai and is giving INTERMITTENT LIGHT to moderate rainfall.

[3] The upper level easterly are fast [20kts]

Today noon, evening more heavy T showers for S,SW,W Tamilnadu.

By noon of 13-Nov, the LOW is expected to push into S-E corner of Arabian sea.

S-W Bay circulation "99W" is still a LOW and moved West... http://ow.ly/i/7xI7W
In next 36hrs, the S-W Bay LOW is expected to push across Srilanka into Gulf Mannar and cross S tip Tamilnadu.. http://ow.ly/i/7xWWn

Due to this movement of 99W LOW...
HEAVY widespread rain expected along N,central,S coast Tamilnadu, Chennai and S coast Andhra for 36hrs.