Mumbai records second highest 24-hour August rain in 10 years
The city and suburbs witnessed the most intense showers of the season between Monday night and Tuesday morning, making it the second highest 24-hour August rain in 10 years at 268.6mm, and also taking Mumbai’s rain tally past the 2,000-mm mark, with almost two months of the monsoon still remaining.
While the red alert (extremely heavy rain across isolated areas) prediction for Wednesday stays, a yellow alert (heavy rain at isolated places) has been issued for Thursday for Mumbai, even as the red alert continues for Thane and Palghar.
Between 8.30pm on Monday and 8.30am on Tuesday, the Santacruz weather observatory, representative of the suburbs and Mumbai, recorded 268.6mm rain, of which 251mm was over a 12-hour period between 8.30pm on Monday and 8.30am on Tuesday. On Tuesday, between 8.30am and 8.30pm, the suburbs recorded 29.3mm rain, while 19mm was recorded in south Mumbai. Borivli recorded the highest rain at 30.2mm, followed by BKC at 28.4mm. The Colaba weather station, representative of south Mumbai, recorded 252.2mm rain over 24 hours, with 214 mm over 12 hours. Mumbai recorded the highest rain across the state between Monday and Tuesday.
Mumbai has received 310mm rain this month, 53% of its August average. The seasonal rain tally on Tuesday evening (from June 1 to 8.30pm on August 4) for the suburbs reached 2,198.9mm, which was 97% of the seasonal target of 2260.4mm. Similarly south Mumbai recorded 2,038mm for the season so far against the target of 2,066mm, covering 98% of the required rainfall.
The highest 24-hour August rain for the decade was recorded on July 30, 2017 at 331.4mm, while the all-time high was on July 23, 1997 at 346.2mm.
The India Meteorological Department (IMD) on Tuesday announced the formation of a low-pressure system over north Bay of Bengal (BoB). “As per the accurate forecast, the Konkan coast including Mumbai witnessed intense showers stemming from the low pressure system in BoB. This trend is likely to continue, and necessary warnings were issued to respective government departments well in advance,” said Mrutyunjay Mohapatra, director-general, IMD.
According to the IMD, the wind speed ranged between 55-60 kmph between 4am and 6am in parts of south Mumbai and 41-45kmph in the suburbs. When cyclone Nisarga had brushed past the city, the wind speed was 92kmph in south Mumbai and 74kmph in the suburbs. “Active monsoon conditions over the Arabian Sea led to high convection and localised circulation that enhanced rain activity, thunderstorms and overnight gusty winds. After a minor break through the day on Tuesday, extremely heavy rain is likely to pick up on Wednesday again,” said KS Hosalikar, deputy director general, western region, IMD.
Independent meteorologists said an offshore trough and a vortex system (localised circulation) were activated on Monday night paving the way for extremely heavy rain. “North Konkan including Mumbai, Palghar, Thane, and Raigad should continue to remain on high alert for the next 48 hours,” said professor Sridhar Balasubramanian, department of mechanical engineering and IDP Climate Studies, Indian Institute of Technology, Bombay.
Like other thunderstorms, the vortex weakened on Tuesday morning leading to a sharp reduction in rainfall, said Akshay Deoras, independent meteorologist and PhD researcher at the University of Reading, United Kingdom.