Wettest July in Mumbai, schools to be shut today

The Brihanmumbai Municipal Corporation (BMC) has announced holiday for schools and colleges in Mumbai on Thursday when schools in Thane and Navi Mumbai will also remain shut.

“Keeping the safety of students as a top priority, a holiday has been declared for all schools and colleges on July 27, 2023. BMC requests all citizens to stay alert, stay indoors and follow instructions from the administration,” said Iqbal Singh Chahal, municipal commissioner and state appointed administrator.

Two IMD observatories saw three-digit rainfall figures — 124 mm in Santacruz and 124.8 in Colaba — between 8.30 am and 8.30 pm. The weather agency categorises rainfall between 115.6 mm and 204.4 mm as “very-heavy” rain, and the downpour that Mumbai experienced over 12 hours qualifies for this category.

Breaking its previous record, the city surpassed 2,000 mm of overall monsoon rain, which is recorded between June and October, within 56 days of the onset of monsoon on June 25 and inched closer towards overtaking the overall average of rainfall figures during the season.

Till Wednesday evening, Mumbai recorded 2,107 mm rainfall with 1,000 mm being recorded in four days, while the average seasonal rainfall is 2,318 mm. This is the second fastest 2,000-mm record, as the mark was achieved in 52 days in 2021.

In July 2005, when the city saw the infamous July 26 floods, the overall rainfall recorded stood at 1,454.5 mm, less than that recorded in July this year.

Despite heavy rain, the catchment areas of the seven lakes that supply water to the city have not seen a significant jump in rain this year. The average water stock in all the seven lakes was 58.93 per cent on Wednesday morning, with an increase of three per cent in 24 hours.

Explaining the reason, an IMD official said that while the low pressure is mainly affecting Mumbai and its adjoining districts, most of these lakes are located in Thane and Nashik districts.

“Westerlies were not penetrating due to mid-level vortex in the shear zone so while Thane, Raigad Palghar are getting good rainfall, the lakes supplying water to Mumbai are not getting good spells as they are located on 19.5° N latitude. If the same shear had been on 20 to 20.5N then lakes supplying to Mumbai would have received heavy rains too,” said the official.

A shear zone is an area filled with opposing winds concentrating heavy rain. “The city is experiencing such an intense spell of rain because of a low pressure and the presence of a cyclonic circulation. Districts like Raigad and Ratnagiri are prone to experience heavier rainfall than Mumbai because of their climatic characteristics,” said Sushma Nair, scientist from IMD, Mumbai.