Now, the S-W Bay circulation is seen along S,S-E Srilanka ... http://ow.ly/i/7JBgc 

GFS expects this circulation to move North upto S-E,central-coast of Tamilnadu in next 24hrs... http://ow.ly/i/7JBjR 
By Saturday, an easterlies trough will be established along central,N-coast Tamilnadu and a weak circulation over Gulf Mannar.
This is how it'll look like on Saturday morning ... http://ow.ly/i/7JBnO 

By evening today into Friday, HEAVY rain expected over S,S-E-coast and central coast (below 12N) Tamilnadu ... http://ow.ly/i/7JBsy 
1:30pm, central,S-E Tamilnadu is already cloudy with some moderate showers around ... http://ow.ly/i/7JBuS 
HEAVY rain alert for S-E,central-coast of Tamilnadu on Friday, Saturday !
and
Afternoon T showers for S,central Tamilnadu.

For N-coast Tamilnadu, Chennai and S Andhra coast...
Moderate Showers expected on Friday.
And
Heavy expected to push in on Saturday.

On Saturday/Sunday, the circulation, LOW is expected to push into Tamilnadu coast !

Weather Instagram at November 27, 2014 at 10:44AM

Chennai - 10:43am, cloudy and warm. At times windy. #weather

from Instagram

Meanwhile, most places in N,N-W,N-central India is having below normal night temps...
Allahabad = 10 C
Delhi = 9 C
Lucknow = 8 C.

Badlapur today had a cool morning after a long time, 17.2 C.
Pune, Nashik = 12.5 C
Mumbai = 21 C.

For N,N-W India, a weak W.D system is expected to affect from tomorrow mid-morning... http://ow.ly/i/7IIGz 
And another W.D trough is expected to affect N,central Pakistan and N,N-W India on Sunday, but less rain forecast for Indian zones!

Tomorrow, rain or snow expected over Kashmir and N Himachal due to W.D.

Analysis indicate the S Bay circulation is now along 5th parallel South of Srilanka ... http://ow.ly/i/7IHZw 

GFS expects the present circulation to drift West along 5th parallel to S-E Arabian sea.
GFS also expects a fresh circulation along central Tamilnadu coast in the easterlies and rains expected to expand.. http://ow.ly/i/7II5R 

Both NAVGEM, GFS models expect the easterlies to affect coastal, interior Tamilnadu, Chennai from Friday morning.. http://ow.ly/i/7IIbK 

Today, from now and before midnight... scattered T showers expected over S-tip,S Tamilnadu and some into S Kerala as well.
Heavy rain expected to start along S-E,S Tamilnadu from tomorrow evening ! ... http://ow.ly/i/7IIjo 
From Friday morning, heavy rain expected for S-E,central-coast, S,central Tamilnadu.

ALERT!!
central,S-E, N-central coast of Tamilnadu is in for HEAVY rain on Friday, Saturday !
#Chennai and N-coast Tamilnadu is expected to get showers only on/from Saturday morning or noon !

Weather Instagram at November 26, 2014 at 02:27PM

Nagercoil - 2:15pm, after a warm noon, now getting ready for a evening T shower. #weather

from Instagram

Weather Instagram at November 26, 2014 at 02:25PM

Karaikal - 8:24am, " Dark as evening here ".. Showers expected to start from tomorrow afternoon. #weather

from Instagram

Easterly wave propagation

 This is the first easterly wave reaching TN coast for this season.  This may be considered as NEM .  The troughs in easterly is vivid and it may bring rainfall to southern coastal regions of TN.

The propagation of easterly wave is shown in the chart.
Dundee image also depicts the propagation from far east. [see wavy cloud pattern]

During past 7 days (till 22-Nov)...
N,N-central,E-central,E India are colder than usual, while W India was hotter.. http://ow.ly/i/7HmXx 

HOT day temperatures to continue along W India, especially over Gujarat, W,N-W Maharastra for next 2 days... http://ow.ly/i/7Hn6K 
Meanwhile COLD mornings to continue over N,N-W,N-central, E,E-central,central India during next 2/3 days!

Monday morning,  Muzaffarnagar (Uttar Pradesh) recorded a min temp of 4.3 C
LOW temps On Monday morning...
Delhi = 9 C
Lucknow, Hissar = 7 C
Srinagar goes below Zero, records -1 C.

Low-level circulation seen over S Bay mouth along 5th parallel followed by a good easterlies seen upto 90E... http://ow.ly/i/7HlQs 
This S Bay circulation is expected to drift West and push into S Srilanka, Gulf Mannar on Thursday... http://ow.ly/i/7Hm1J 
The easterlies is expected to reach most of Tamilnadu coast on Thursday evening.
Heavy rain ahead on 28,29,30-Nov for coast,interior TN

T showers expected over S Tamilnadu "again" from late-evening today !!
Entire S,S-E coast, central coast Tamilnadu is in for Heavy rain from Thursday evening... http://ow.ly/i/7Hmlv 
By Thursday night or Friday mid-morning... showers will reach N-coast Tamilnadu and Chennai.