It happened 6 out of 9 times in Santa Cruz (Mumbai) between 1975 and 1990 resulting in more than 20 cm rainfall in 24 hours. Such a combination was present in 4 out 8 times in the same period when more than 20 cm rainfall was recorded in a single day in Colaba, Mumbai.
The corresponding fortnight starts with this combination and moon in cancer. Somewhere in the east coast of India, heavy rain must be lashing the shores. Chennai is not in the line of those rains. At the end of the 12th day, the Garbottam indicates this.