Calcuttans who thought the four-day-old depression would pass and the sky would clear by Friday will have to wait for the weekend to spot a silver lining. The weatherman on Thursday warned of heavy rain in Calcutta and elsewhere in Bengal over the next 48 hours.
Belying expectations that the depression would move north-west into Madhya Pradesh, it veered in a north-easterly direction, crossed northern Orissa and hovered over Ranchi and its neighbourhood on Thursday morning. By the evening, the system reached Malda, in north Bengal.
In Calcutta, the weather office recorded 12.2 mm of rain till 5.30 pm on Thursday.
The depression, located over the Bay of Bengal last Sunday, lay 100 km south-east of Raipur early on Wednesday. “We had expected the depression to move further north and cross Madhya Pradesh. But last night, it started inching towards northern Orissa and reached Ranchi on Thursday. That ensured that Calcutta would not be free from rain for another two days,” said a senior official of the regional meteorological centre in Alipore.
Director K.K. Chakraborty of the Met office weather section said that as the depression had weakened considerably, the weather was likely to improve in Calcutta from Friday afternoon. “The intensity of the rains has become much less. However, I don’t think the sun will come out on Friday,” he added.
Met officials said that the depression had weakened since Wednesday into a well-marked low-pressure zone and is expected to peter out in the next two days. Under the influence of the current system, heavy to very heavy rain is likely over Calcutta and the rest of Bengal, Bihar, Jharkhand and Tripura.
“We expect the low pressure to cross over to Bangladesh and then into Assam. But then, it is likely to fizzle out. So, it is unlikely to cause significant damage,” an official said.
“But, the system still has a lot of cloud and moisture and is expected to cause heavy showers in Calcutta and its adjoining areas of Birbhum, Murshidabad, Nadia and the north Bengal districts like Jalpaiguri and Cooch Behar and also Sikkim,” the official added. The Met office has warned fishermen not to venture out in the coastal areas during the next 24 hours.
Explaining the north-easterly movement of the depression, officials said that as it moved northwards, it came into the path of strong winds from the north-west that gradually drove it in a north-easterly direction.
Calcuttans woke up to an overcast sky on Thursday and the weather showed signs of clearing around 9 am. But, an hour later, the sky darkened and it started pouring in many parts of the city and its adjoining districts.
Faced with the first depression at the onset of the cyclone season — that begins in October and lasts till mid-December — the officials at the Met office have started scanning the radar and satellite pictures for formation of storms or depressions over the Bay of Bengal.