A sharp spell of rain struck the city on Friday afternoon, triggering waterlogging in some pockets and stalling traffic on busy thoroughfares.
But for the second time in three days, the distribution of the rainfall was skewed.
Around 1.30pm, when the intensity of the rain had marred visibility in New Market and Gariahat, Dum Dum got a drizzle. Around the same time, New Town was bone dry.
The Met office recorded around 32mm of rain till Alipore on Friday. Almost all of the rain happened between 1pm and 2.30pm.
In Met parlance, 60mm of rain in 24 hours qualifies as heavy.
The rain led to choked traffic in several areas.
A woman travelling to Esplanade said it took her nearly an hour to reach Chittaranjan Avenue from Amherst Street, a distance of around 3km, around 1pm. Usually, it takes around 15 minutes to cover the distance.
The Met office attributed the skewed distribution of rainfall to weak monsoon currents and local thunderclouds. “The monsoon trough is passing through Patna in Bihar, and Sriniketan in Bolpur. But in the absence of any system over the Bay of Bengal, there is no mechanism for propelling sufficient moisture into south Bengal for the formation of thunderclouds that would cause uniform rain,” said a Met official.
“Whatever moisture is entering south Bengal is leading to the formation of local clouds,” he said. The districts of north Bengal are tipped to get heavy rain over the next few days.
In the absence of any system, the moisture is likely to travel upwards, get blocked by the Himalayas and cause rain in north Bengal and Sikkim.
The volume of rain is likely to go up in Kolkata on July 31 and August 1, when the trough is expected to come down, closer to Kolkata, an official said.
Before Friday, parts of Kolkata and neighbouring areas got sharp spells of rain on Wednesday afternoon while some other parts got only clouds. Alipore had got around 16mm of rain that day, while Salt Lake got 25mm. The monsoon deficit in Kolkata stood at 44 per cent on Friday, the Met office said.