Parameters on the Wednesday evening chart coincide with the withdrawal of the SW Monsoon from complete Sindh region of Pakistan. 

Setting the tone, the SWM is likely to retreat from rest of Pakistan and Western Rajasthan in the next 2 days, that is by Saturday, 22nd, evening.

Thursday, 20th/Friday, 21st: 
Heavy thundershowers on the increase in all regions of interior Maharastra, i.e. Madhya Maharashtra, Marathwada and Vidharbha. 
Pune, Satara, Sangli, Nasik and ghat staions can possibly get thundershowers Friday. 
Nagpur can get convective rains. 
N.I.Karnataka will also get isolated thundershowers in some pockets. Northern AP can get thundershowers, with likely rain in Hyderabad. 

Very light rainfall, with thunder, likely in few districts of Saurashtra. Surat and Bharuch districts can get a stray thundershower on Friday evening.

NW India, and Delhi NCR will be clear and dry, with days reaching 34c, and night around 24c. SW Monsoon has not withdrawn from NCR and may retreat middle of next week.

More detailed article in vagaries.

Chennai - already 1:15pm one or two small showers seen over s, s-s-w at around 40km from city.

Chennai - 1:15pm, conditions are good for a t.shower. good preliminary t.cell formation seen over city.

RT @aknarendranath: @weatherofindia Himachal receives season's first snowfall - The Times of India http://t.co/wkfG0ydk

5:30pm, Heavy rain seen over central,E,S-E.Uttarpradesh, S.Orissa, N,N-E.Andhra and Bihar... http://ow.ly/i/WCqH

5:30pm, T.showers also seen over S-E coast of Tamilnadu ... http://ow.ly/i/WCqH

13 killed in rain-related incidents in UP ... http://ow.ly/dNdn5

‘Monsoon fevers’ claim 36 lives in Rajasthan ... http://ow.ly/dNdp0 

Heavy rain for W,N-W,central.Uttarpradesh due to the weak UAC ... this'll last for next 24hrs... http://ow.ly/i/WACH

Scattered rain for E,E-central India will continue till 21/22-Sep ... http://ow.ly/i/WADm

Scattered rain for most of N-E states will continue till 22/23-Sep.

Rain for Orissa, S.Chatisgarh to continue till 22-Sep ... http://ow.ly/i/WAFy

From today, scattered rain are expected to push into N,N-E.Andhra and persist till 22/23-Sep ... http://ow.ly/i/WAFT

Showers along S,S-central.Andhra, S-E.Karnataka and N-E.Tamilnadu, #chennai to persist till 21-Sep.

From 20-Sep almost NO rain forecast ALL along West & S-W coast !!

Offshore trough along S-W coast has almost vanished .. it's expected to last another 2 days... http://ow.ly/i/WAuZ

Seasonal LOW over Pakistan is loosing strength rapidly ... Signalling the END of Monsoon for N,N-W India .. http://ow.ly/i/WAwz

Low level circulation still persists over central Uttarpradesh .. expected to slightly drift N-W and vanish in 24hrs.. http://ow.ly/i/WAxt

Another low level circulation seen over N.Chatisgarh & Orissa.. extending into N-W.corner Bay ... http://ow.ly/i/WAxt

A weak Low level circulation expected over Bihar & Bengal in next 24hrs and it'll persist till 20-Sep.. http://ow.ly/i/WAzr

UAC can be seen over N-W.Uttarpradesh .. and it'll vanish in another 24hrs ... http://ow.ly/i/WAAn

A weak UAC is expected along N.Tamilnadu & #chennai coast in next 24hrs .. http://ow.ly/i/WABb 

2pm, W.D over Kashmir, Himachal is slowly moving East... http://ow.ly/i/WAot

2pm, Fresh showers seen over N,N-E.Andhra, S.Orissa, S.Chatisgarh, E.Uttarpradesh, Bihar, Jharkand & Bengal.. http://ow.ly/i/WAot 

NOGAPS model suggests that Monsoon will go dry over most of N,N-W,W,E,E-central India around 25-Sep .. http://ow.ly/i/WAn4