| GROUNDED, BUT ALIVE: Squalls through Wednesday night uprooted several trees across the city. One victim opposite Calcutta zoo came crashing early on Thursday, creating office-hour car chaos and wreaking havoc on the birds' nests in it. A good number of birdlings died, but Metro spotted one of the lucky survivors. Picture by Sanjoy Chattopadhyaya
Calcuttans could be in for a wet Holi this year ' even without buckets and balloons filled with coloured water.
Met officials on Thursday said the prevailing squally weather is likely to continue till Friday evening, from when things are expected to clear gradually.
Heavy pre-monsoon showers, accompanied by gusty winds, lashed Calcutta and its adjoining areas throughout Wednesday night and most of Thursday. The weather office recorded 46.6 mm of rain till 5.30 pm on Thursday.
The squall spelt the doom for a dozen trees in the city and its adjoining areas.
Five trees came tumbling down on Park Street and Chowringhee, in Hazra and New Alipore. Three trees were uprooted in Salt Lake.
Acting deputy director-general of meteorology in Alipore, K.K. Chakraborty, said a squall warning had been sounded for Friday in Bengal, Bihar, Jharkhand and Tripura, with a wind speed of 70 to 80 kph. Fishermen had also been advised not to venture into the high seas.
The good news was how the squall in the city dragged down the day's mercury, with the maximum temperature dipping to 25.6 degrees Celsius on Thursday, nine degrees below normal.
Officials said the build-up to the prevailing squall had begun last Sunday, when the maximum temperature started rising. By Tuesday, heat and humidity plagued Calcutta, with the maximum temperature rising to 37.7 degrees, four degrees above normal.
'During that period, a lot of moisture was being sucked in from the Bay of Bengal, following an upper-air circulation. The moisture fed this hot spell for a few days and, by Wednesday, huge columns of convective clouds ' 18 to 20 km tall ' had formed over vast areas of Jharkhand, Bengal and the adjoining areas, leading to the squall and thunderstorm,' explained Chakraborty.
Officials said from Tuesday evening, the incursion of moisture became heavier, as it was sucked in from the Arabian Sea as well.
'The combined effect of a trough of low pressure spread from Saurashtra to Tripura and two upper-air cyclonic circulations over Jharkhand and its neighbourhood, and over Sikkim and north Bengal, has led to heavy incursion of moisture and the squally weather,' an official added.
Heavy rain through Wednesday night has depleted the volume of cloud cover over Calcutta. 'Now, the cloud columns are six to eight km tall but capable of delivering more rain,' said director of the weather section G.C. Debnath.
With the surface cooling off considerably, the chances of such intense cloud formation have diminished, said the weather office.
'So, we expect that the day temperature will rise and the sky will begin to clear from Friday night,' an official said.