The Telegraph
Since 1st March, 1999
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Wanted, right trigger for rain

The heat and the humidity stifling the city could stay on for the next two days, warns the weatherman.

'As things stands now, there is no possibility of rain in Calcutta and its neighbourhood during the next 48 hours. The last time the city received any significant rain was on Thursday night,' said a senior official of the Alipore Meteorological department.

But what explains the mystery of the missing monsoon after a low-pressure trough over Gangetic West Bengal, Jharkhand and north Orissa had helped bring the rains to south Bengal on June 6, two days ahead of schedule'

'The low-pressure trough gradually moved northwards and lay over Bihar last Thursday. This movement of the low-pressure trough away from Calcutta weakened the monsoon current over this region,' explained the official.

The trough on Monday extended from north Bihar to Arunachal Pradesh, across sub-Himalayan West Bengal and Assam. 'For normal monsoon rains, we need a low-pressure trough over south Bengal with an accompanying cyclonic circulation (anti-clockwise movement of air) to strengthen the monsoon current over Gangetic West Bengal,' added the official.

Just high humidity, causing the horrid sweat factor, is not enough. 'We have lots of moisture coming in from the Bay of Bengal, but we need a favourable atmospheric system to trigger the rains,' explained the weatherman.

The maximum temperature had soared 'by at least 4 degree Celsius' over the past five days, said Met officials. And the 'extremely high humidity level' is making the heat almost unbearable.

Met officials further said that though the monsoon had reached north Bengal eight days ahead of schedule, on May 20, its progress since then has been uncharacteristically slow.

'The situation is likely to remain the same for the next couple of days,' concluded a Met official.

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