Prediction of very heavy rainfall over the next 48 hours in Mumbai was made by the India Meteorological Department (IMD) today.
In its forecast for Mumbai and suburban areas, the IMD predicted intermittent or continuous rain or showers with few heavy spells beginning from 10 am on September 21 progressing to very heavy rains during the next 24 to 48 hours, Joint secretary of the State Disaster Management Authority (SDMA), Rajiv Nivatkar said.
"Exceptionally heavy rains are expected in the city from the morning of September 23," he said.
Till September 23, very heavy rainfall is also expected in Konkan, Marathwada, Central Maharashtra and Vidharbha regions, he said.
The cyclonic circulation now along the coast of Andhra Pradesh is gaining strength. Coupled with that, another cyclonic circulation is developing over the Arabian sea off the Mumbai coast, the official said.
"Under the influence of these weather systems, there is likely to be increase in rainfall in Mumbai and northern districts of Thane and Palghar," he said.
SDMA director Suhas Diwase, when asked whether heavy rains could leader to 26/7 (2005) deluge-like conditions, said if it rains about 150 mm in 24 hours then there would be no harm.
"However, if the same quantum of rainfall occurs in just two hours, then it leads to flooding. On that fateful day in 2005, almost 92 mm rain fell in just in an hour and around 300 mm in the next few hours which led to chocking of Mumbai," he said.
Meanwhile, between September 21 and 22 isolated heavy spells are expected in North Konkan (Mumbai) and South Konkan (rest of Konkan region).
Yesterday, Thane and Palghar districts recorded 401 mm rainfall.
Mr Nivatkar said monsoon activity that revived itself since the last week has so far almost achieved the comparative average annual rainfall.
This year, the rainfall in Maharashtra till September 18 has been 972 mm, whereas comparative annual rainfall has been 1,050 mm. This year, the rainfall has crossed the average rainfall of last two years, which was in the range of 660 mm to 670 mm, he said.
According to Mr Nivatkar, good rainfall has resulted in most of the major and medium irrigation dams getting brimful of water, except two dams in Majalgaon (Beed district) and Manjra (Latur district) where the water stock is still not much.