Thunderstorm with heavy to very heavy rain is likely to occur at isolated places over Tiruvannamalai, Ranipettai, Vellore, Tirupattur, Krishnagiri, Dharmapuri,Salem, Erode, Namakkal, Coimbatore and Tiruppur districts of Tamilnadu.
Thunderstorm with heavy rain is likely to occur at isolated places over Kallakurichi, Villupuram, Tirunelveli, Kanyakumari and Chennai districts of Tamilnadu.

Light to moderate rain is also likely to occur at most places over rest districts of Tamilnadu, Puducherry & Karaikal area.

HEAVY RAINFALL WARNING

Today (19.11.2021): Heavy to very heavy rain is likely to occur at isolated places over Tiruvannamalai,Ranipettai, Vellore, Tirupattur, Krishnagiri, Dharmapuri, Salem, Erode, Namakkal, Coimbatore and
Tiruppur districts of Tamilnadu. Heavy rain is likely to occur at isolated places over Kallakurichi, Villupuram, Tirunelveli, Kanyakumari and Chennai districts of Tamilnadu.
Tomorrow (20.11.2021): Heavy rain is likely to occur at isolated places over Krishnagiri, Dharmapuri, Tirupattur, Erode, Kallakurichi, Salem, Tiruvannamalai and Cuddalore districts of Tamilnadu.

THUNDERSTORM WARNING

Day 1(19.11.2021) to Day 4 (22.11.2021): Thunderstorm with lightning is likely to occur at isolated places over Tamil Nadu, Puducherry and Karaikal area.

LOCAL FORECAST FOR CHENNAI CITY AND NEIGHBOURHOOD: For next 24 HRS: Heavy to very heavy rain is likely to occur.

Reference:
http://imdchennai.gov.in/tn_fc.pdf
http://www.imdchennai.gov.in/hrw_district.htm