Monday, 30th October 2017

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Relief from heat blowin’ in the wind

Moderate rain likely but not enough to make up for monsoon deficit

By Debraj Mitra in Calcutta
  • Published 17.07.19, 4:13 AM
  • Updated 17.07.19, 4:13 AM
  • a min read
Pedestrians and cars on Mayo Road during Tuesday’s showers Picture by Pradip Sanyal

Gusty winds and a sharp spell of rain on Tuesday afternoon brought temporary respite from the heat and humidity that the city had been reeling under for the past couple of days.

Moderate showers are expected over the next two days as well but not enough to make up for the huge monsoon deficit the city is staring at, weather officials said.

The season’s cumulative rain deficit stood at 73 per cent on Monday. This June was the driest the city has witnessed in a decade. July has not been much better with only around 40mm of rain in the first 15 days.

The first fortnight of July had received 96.6mm rain last year and 308.5mm in 2017. The normal rain count for the period is 170mm.

The Telegraph

A glimmer of hope has emerged in the form of a trough of low pressure cradled in the foothills of the Himalayas that started descending on Tuesday because of a cyclonic circulation over the Bay of Bengal off the Myanmar coast.

It is the trough that brought heavy rainfall in the northern districts of Bengal over the past few days. South Bengal, too, is likely to get some rain in the next few days.

“A cyclonic circulation has formed over east-central Bay of Bengal off the Myanmar coast, 5.8km above the sea surface. This has helped bring down the trough line, which now runs from northwest Rajasthan to northeast Bay of Bengal, across Haryana, southern Uttar Pradesh, Bihar, Jharkhand and Gangetic Bengal. The shift means less rain in north Bengal and more in south Bengal,” said Sanjib Bandyopadhyay, deputy director general, India Meteorological Department, Calcutta.

But the circulation is not yet strong enough to bring the heavy rain needed to reduce the huge monsoon deficit for Calcutta. “The cyclonic circulation is quite far from the sea level and unless it comes closer to the surface, chances of heavy rain in south Bengal are slim,” Bandyopadhyay said.

Tuesday’s rain was caused by local clouds, the Met office said. Pent-up heat and high humidity had led to the formation of thunderclouds.

The sky darkened a little before 1pm on Tuesday. The winds clocked a maximum speed of 59kmph at 12.55pm, an official in the Alipore observatory said. The rain lasted for around 30 minutes. Patuli was the wettest with 50.8mm rain.