Highest July day rain for Bengaluru since 2012; more forecast on July 22

Bengaluru received as much as 82.6 mm of rainfall in the 24-hour period ending 8.30 am on Thursday, the highest for a July day since at least 2012.

The city is forecast to receive another spell of heavy rainfall on Friday, and the weather department has issued a yellow alert.

The thunderstorm on Wednesday night was mostly concentrated in the city's central and eastern parts and was unaccompanied by squalls or strong winds, data from the India Meteorological Department (IMD) shows.

A high daytime temperature, coupled with the availability of moisture and a "mountain effect", was behind the thunderstorm, explained A Prasad, Scientist-D at the IMD’s meteorological centre in Bengaluru.

"There's a trough (an elongated area of low pressure) from South Interior Karnataka to Comorin (southern Tamil Nadu).

"This caused winds to converge and clouds to form between the Nilgiris, Bengaluru, Tumakuru and Hassan," Prasad told DH. "Bangarpet and Bengaluru received the bulk of the rain."

At 90.2 mm, Bangarpet reported the most rain, according to the IMD. But as per data from the Karnataka State Natural Disaster Management Centre (KSNDMC), Vagata, a village in Hoskote taluk, received as much as 107.5 mm of rain.

In Bengaluru, the maximum temperature on Wednesday stood at 31ºC, followed by a spell of intense rain in the city's central and eastern areas late in the night. Other parts of the city received moderate rains.

The IMD observatory at the HAL airport recorded 33.3 mm of rain. Jnanabharathi (27.5 mm), Uttarahalli (21 mm), Yelahanka (KSNDMC) (14.5 mm) and Anekal (10 mm) recorded moderate rain.

The downpour flooded streets in the Central Business District (CBD) with Cunningham Road being the worst hit. The BBMP control room received tree fall complaints from Girinagar and Thyagarajanagar.

On Friday, Bengaluru is expected to receive about 70 mm of rain, mostly late in the evening or night, Prasad said.