While the Met department pegged the total average rainfall in the suburbs, between 8 am on July 1 and 8 am on July 2, at 375.22 mm, isolated localities in the eastern and western suburbs received over a 100 mm in excess of the average.
The maximum 24-hour rainfall in any one locality was recorded to be 479.56 mm at the Dindoshi fire station in Malad (East). The Brihanmumbai Municipal Corporation’s weather apparatus also recorded very high rainfall readings at Kandivali fire station (455.91 mm), Malad fire station (451.32 mm), Chincholi fire station (447.54 mm), Malvani fire station (447.52 mm) and Goregaon fire station (412.25 mm).
These localities form a nearly contiguous belt in the northwest part of the financial capital, wedged between the west coast and a national park. A wall collapse around midnight, in which at least 16 people were declared dead, also occurred in this belt in the Kurar locality of Malad (East).
In the eastern suburbs, very heavy localised rainfall was recorded at Vikhroli fire station (403.55 mm) and Kurla fire station (399.49 mm).
Previous extreme one-day rainfall data for Mumbai suburbs records the heaviest ever precipitation of 944 mm on July 26, 2005. Monday night’s rainfall comes closest to that record. Other very heavy one-day rain recordings include 399 mm on June 10, 1991, and 346.2 mm on August 23, 1997.
The Met department’s rain gauges at the Colaba and Santacruz observatories showed overall average rainfall recorded at 137.88 mm and 375.2 mm in 24 hours, ending 8.30 am on Tuesday. The India Meteorological Department had accurately predicted that the city and suburbs will receive heavy and “localised” rainfall.
At 2 pm on June 30, the IMD’s forecast for the week said a low pressure area had formed over the Bay of Bengal and was likely to develop into a depression in the next 48 hours. The westward movement of the low pressure system will bring “heavy to very heavy falls at a few places and extremely heavy falls over isolated places”. The prediction was for Madhya Pradesh, Odisha, Maharashtra and Goa.K S Hosalikar, deputy director general, IMD, at the Mumbai regional centre posted real-time updates too. At 12.30 am on Tuesday, a ‘Nowcast’ said there were “very intense spells” of rain likely to continue in Mumbai, Palghar, Thane and Raigad for the next four hours.
Hosalikar tweeted once again around 1 am to say the local forecast for Mumbai for the coming 24 hours included chances of “intermittent heavy showers with isolated extremely heavy rainfalls”.
In fact, the heaviest rainfall recordings by the automated weather stations of the BMC and the IMD were between 11 pm and 3 am. In the one hour between 11 pm and midnight, the device at Kurla fire station recorded 75.94 mm rain, the one at Borivali fire station recorded 70.61 mm rain. Between midnight and 1 am, Malad received 76.96 mm of rain. The western suburbs stretching between Jogeshwari and Borivali saw an intense spell of rainfall in three hours between 11 pm and 2 am, with Malvani recording 168.91 mm in this period, Chincholi 167.87 mm, Versova 143.02 mm and Malad 178.3 mm.
“We post regular updates on our Twitter and Facebook accounts and also have WhatsApp groups at the state and district levels where updates are posted regularly for farmers, media, and others,” Hosalikar told The Indian Express on Tuesday evening.
“The IMD has also been broadcasting its forecasts via email through the National Informatics Centre. “We have hotlines with the BMC, police and fire departments and are in constant touch with them.