6:30pm, Cyclone Murjan.. Heavy rain seen over N,central,E of Somalia ..while the system is slowly crossing into Somalia http://ow.ly/i/13EYH 

Murjan was making a unusual tropical cyclone landfall in Somalia .. http://ow.ly/eLa0r 

5:30pm, Showers seen over S-W.Karnataka, N,central Kerala.. Meanwhile S-E Bay circulation persists .. http://ow.ly/i/13EXd 

Low level circulation is over S-E corner Bay .. http://ow.ly/i/13DdR

S-E Bay circulation is expected to move W-N-W and then West.. IMD-GFS expects it to be a Depression and reach N-N-E.Srilanka on 29-Oct.

IMD-GFS model forecast of circulation on 29-Oct.. http://ow.ly/i/13Dfl

IMD-GFS expects the present S-E.Bay circulation to become as a Marked LOW and nothing more .. on 29-Oct.. http://ow.ly/i/13Dgg

N-E monsoon current is expected to pick strength along N,central Tamilnadu coast by noon of 27-Oct.. http://ow.ly/i/13Dhz 

3:30pm, Cyclone Murjan is sliding S-W and still very near to Somalia coast .. http://ow.ly/i/13DcF 

NOGAPS still persists with a Depression from Bay to hit Central/N.Tamilnadu coast on 29/30-Oct.. http://ow.ly/i/13Cw8 

Latest NOGAPS suggests that monsoon moisture will be back along Tamilnadu coast on evening of 27-Oct.. http://ow.ly/i/13Cve 

Today's moisture along N.Tamilnadu coast & #chennai will vanish in next 12hrs.. and almost NO rain forecast till 28-Oct

From today evening almost NO rain forecast for entire Tamilnadu & Kerala till 27/28-Oct.

Cyclone Murjan will cross into Somalia by evening, Today ... http://ow.ly/i/13Cs8 

RT @aknarendranath: #Delhi - Mercury dips to 16.4°C, nip in the air here to stay - TOI http://t.co/c52ITzWh @weatherofindia 

The low pressure in the Bay is now situated at 10N and 96.5 E. Core pressure at 1007 mb, it has entered the Bay area, hence vagaries numbers it as BB-10.
BB-10 is now deepening with favourable conditions and SST at 30c. 

Now, as we have earlier discussed possibilities of the tracks before, the WD factor seems to be out of question as far as the timing of this BB-10 is concerned. 
There is no WD coming.
In fact, what is favourable for TN is the possibility of a High pressure developing around the Bangladesh region. 
With this, we could very well see BB-10 tracking due West...and hope for good rains along TN and AP areas when it reaches land, as system can strengthen upto depression at least.

more on vagaries.