Yesterday saw electrifying midnight thunderstorms in Chennai with South Chennai & Southern suburbs enjoying the benefit of intense rainfall little after midnight till about 2 AM. In what looked like ending up as a hot and dry day things got better as the evening progresses with thunderstorms finally forming around Tiiruvannamalai / Polur area that made their way to the coast intensifying as the reached closer to Chennai and providing rains to the southern areas of the city. 
A narrow area got benefited by these midnight thunderstorms in Chennai as they moved from SW to NE. The rest of the city were left to passing showers with the IMD observatory in Nungambakkam recording only 1 mm while the COMK AWS in Anna Nagar also recorded only 1 mm during the same time.
Things look good for rains to continue in many parts of Tamil Nadu today as well though with the wind directions changing to W/NW to E/SE today we might look at possibly Tiruvannamalai, Vellore & Kanchipuram districts getting benefited once again. The area to the Southeast of Bangalore around Salem / Dharmapuri shows conducive conditions for thunderstorm development as well. Delta region around Trichy could see another day of thunderstorms today as well if things go according to what models expect.
Taking into account the wind pattern for Chennai to benefit we need the thunderstorms to form to the W/NW of us roughly around Tirupati / Cuddapah region of Rayalaseema. As of now models indicate lesser probability of thunderstorms developing around this region, nevertheless we cannot rule out the possibility of thunderstorms developing in South AP area under convective aid in case the skies clear up from overnight thunderstorms. Temperatures are likely to stay around normal or slightly below normal for most part of Coastal Tamil Nadu