Latest analysis show a low-level trough seen over S-E corner Arabian sea and circulation along S-E coast Tamilnadu.. http://ow.ly/i/71qdM 

Before morning...
More rain ahead for S Kerala and S tip Tamilnadu !
27-Sep, noon, evening...
HEAVY scattered rain again over W-ghats Kerala, W,S,S-central Karnataka, N,W-ghats,S,central Tamilnadu !
27-Sep...
Scattered T showers will pop over S,S-central,N-E Andhra ... http://ow.ly/i/71s7d 

India's Mars Orbiter Mission sends first images of Red Planet..  http://ow.ly/BZuK8 
we are following @MarsOrbiter

RT @aash_tvm: മൂടിക്കെട്ടി നിന്നതൊക്കെ ഇപ്പൊ മഴയായി പെയ്യുകയാണ്... Raining here at #Trivandrum @weatherofindia (4pm)

4:30pm, HEAVY T showers over S,S-central,N-E Tamilnadu, S,central Kerala, S-central Karnataka ... http://ow.ly/i/716PJ 

#Chennai - Mini showers seen over W,S-W,N-W from city at 50 to 80km.

Very less chance of T showers popping over city.

Latest analysis show that low-level circulation is over S tip Tamilnadu and in next 48hrs it'll drift West into Sea http://ow.ly/i/712TH

Due to this circulation, before morning of 27-Sep...
HEAVY scattered T showers for S,W,N,central, W-ghats Tamilnadu, W-ghats Kerala.
Today again, HEAVY T showers expected over W-ghats Karnataka, S,S-central Karnataka and #Bangalore ... http://ow.ly/i/7135Q
Today evening, midnight... T showers also expected over S,S-central Andhra.

Today, scattered T showers also expected to pop along W-ghats, W,S-W Maharastra.

25-Sep, Bangalore records 13cm

#Bangalore - 25-Sep, "Cloud burst" records 13cm.
" 90 mm in just an hour "

Bangalore: Heavy rain throws normal life out of gear ... http://ow.ly/BXHZv  ... http://ow.ly/i/712ac 
13 cm of rain batters Bangalore in 5 hours, man found dead ... http://ow.ly/BXI6l 

My intution and ensuing SWM torrential rain.

It has been observed that the Indian Ocean High near Mauritius is extra ordinarily of higher value.  This pressure anomaly is unusual.  Its teleconnection will reflect in India as we saw flooding in [1] J&K and recent flooding in Mehalaya & Assam.  I see a symmetry with this flooding and pressure anomaly. My fear is yet another torrential rain along south / SW India  I have given few surface charts and other wind profile data for reference/ comparison.  It is NOT a forecast. But it is my intuition. Veteran may please correct me, if it is wrong.

24.09.2014

25.09.2014

 This is 24.09.2014 / 16LT chart where the pressure is mounting and the below one is chart depicting 1039hPa. 
The other weather phenomenon like the trough forming near KOMORIN sea etc to give rainfall

However the Southern Hemisphere wind sinking at 30Deg South Latitude  [General Circulation] is NOT known to me.

veteran must clear my doubt

25.09.2014 /12Z winf

How ever preparedness to encounter torrential rain is also good. [it may happen or may NOT, that is different]

Weather Instagram at September 25, 2014 at 01:45PM

#chennai - 1:25pm, hot, humid and with good sea breeze. Photo of mini T cell over N suburb near Ponneri. #weather

from Instagram

#chennai - 1:45pm, lots of mini rain systems has popped over NW,W suburbs of city. Expected to move South.

6:30pm, Lots of T showers seen over S,central,W-ghats Karnataka, S-W Maharastra, S Tamilnadu ... http://ow.ly/i/6ZDbA 

Today, the low-level trough from Bangladesh to W-S-W Bay persists ... http://ow.ly/i/6ZApB
In next 24hrs, a low-level circulation is expected over S Tamilnadu and expected to drift West or W-S-W ... http://ow.ly/i/6ZAsU
WRF model suggests, on 25-Sep, low,mid-level circulation will be along S tip Tamilnadu, S tip Kerala ... http://ow.ly/i/6ZADz

An upper,mid-level trough seen from N Bihar to S Bengal, N Bay ... expected to persist and drift East in 2 days.. http://ow.ly/i/6ZBPo 
In 12hrs, an upper-level W.D trough is expected to touch N,N-central Pakistan and will drift East during next 2 days http://ow.ly/i/6ZBPo

Rainfall alert for next 42 hrs
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Before morning of 25-Sep...
T showers will persist over N,N-W,central,S, W-ghats of Tamilnadu .. http://ow.ly/i/6ZCd7 
Early hrs, morning of 25-Sep..
T showers expected along Kerala coast, S tip Tamilnadu and Lakshadweep.
Tonight, HEAVY T showers possible over N,central Bengal, Sikkim, N,central Bangladesh and into central zones of N-E states.

Due to W.D...
scattered rain for N Pakistan and into Kashmir, Himachal during next 24hrs !
Most of N,N-W,W,central India is expected to remain DRY during next 2 days !

Due to formation os circulation over S Tamilnadu..
HEAVY rain expected over S tip, w-ghats of Tamilnadu on 25-Sep ... http://ow.ly/i/6ZCwu 
25-Sep, noon, evening...
T showers again for N,N-E,N-W, central Tamilnadu, S,central Karnataka and S,central Andhra.

#Bangalore - 25-Sep, more HEAVY T showers expected for city, suburbs !
#Chennai - 25-Sep, from 11:30am to 5pm a localized T shower will pop over S-W,W,N-W suburbs.
Less rain expected for city and along coast !
#Chennai - Today afternoon rain over Pallavaram, Polichalur zone.
IWM Polichalur station records 12.9mm of rainfall.