The altogether welcome showers on Monday evening brought a palpable drop in temperature, from a record 37.6 degrees Celsius on Sunday to 36 degrees on Tuesday.

But when residents exchanged notes on the unexpected downpour, a rather curious picture emerged of the fractured rainfall pattern in the city — a pattern that scientists say is consistent with pre-monsoon thundershowers.

While residents of Gandhinagar reported a downpour steady enough to impede traffic, those of Hebbal and beyond had to shelter themselves from a veritable torrent and strong winds, and as for East Bangalore, most parts remained bone dry.

Indeed, the meteorological centre's rain gauges corroborate these accounts: the city centre received 21.8 mm, HAL “trace” rain, and Yelahanka 45 mm on Monday. Tuesday too saw a similar rainfall pattern with the city recording 5.4 mm, HAL 1.6 mm and Yelahanka 33.8 mm.

This local variation in rain is typical of thundershowers, where clouds are five to 10 km in horizontal size and move relatively rapidly, explained G.S. Bhat, Chairman of the Centre for Atmospheric and Oceanic Sciences at the Indian Institute of Science.

“Unlike during monsoon depression when clouds are large and can blanket the city, thunderclouds are formed through convection and can be a fairly randomly scattered,” said Prof. Bhat.

Rain and thundershowers are likely to continue for the next two days, said the duty officer at the Meteorological Department.

Staggering variation

This variation has little to do with micro-climate — often determined by tree cover or concretisation — that can create islands of relative cool and heat within the city, he said. For instance, a recent study of Bangalore's green cover by scientists at Ashoka Trust for Research in Ecology and the Environment had revealed a staggering 10-degree difference in temperature between roads that had a canopy and those that did not.

Power cut

Several parts of the city plunged into darkness for the better part of the evening on Tuesday. Frequent power outages and long hours of power cuts were witnessed in several areas, particularly in the southern parts of Bangalore.

Some areas in Ullal, Rajarajeshwari Nagar, Padmanabhanagar and J.P. Nagar witnessed long power cuts. When contacted, Bescom officials blamed it on the rains. “The scheduled and unscheduled power cuts are because of power shortage. But these longer power failures are generally due to tree fall,” the official explained.

Keywords: Summer rain

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