Kolkata is likely to receive heavy rain on Thursday as a deep depression over the Bay of Bengal crosses the Andhra Pradesh-south Odisha coast and moves west-northwestwards into central India, according to a weather bulletin cited by the Met office.
The system was located around 30km south-southwest of Kalingapatnam in Andhra Pradesh, 90km east-northeast of Visakhapatnam and 160km southwest of Gopalpur in Odisha in a bulletin issued around 7.45pm on Wednesday. It was expected to cross the north Andhra Pradesh and adjoining south Odisha coast between Visakhapatnam and Gopalpur, close to the southwest of Kalingapatnam, within three to four hours.
Kolkata had already experienced rain since Wednesday morning. The Alipore Met office recorded around 28mm of rain until 8.30pm, while the sky remained cloudy and overcast for most of the day apart from a brief period in the forenoon. The maximum temperature reached 29.6 degrees Celsius, three notches below normal, and is expected to remain below 30 degrees on Thursday.
The forecast indicated that rain would intensify across several parts of south Bengal. Very heavy rain was likely in East Midnapore, West Midnapore and Jhargram on Thursday. Heavy rain was expected in South 24-Parganas, Bankura, Purulia, West Burdwan, Birbhum, Howrah and Kolkata. On Friday, heavy rain was forecast in Bankura, Purulia, West Burdwan and Birbhum, with the intensity of rain across south Bengal likely to decrease from Saturday.
The weather system also carries implications for coastal districts and transport conditions. Moderate to strong gusts are expected across the state. Squally winds reaching speeds of 45-55kmph, with gusts up to 65kmph, were likely along and off the Bengal coast until September 25, according to the bulletin. Very rough sea conditions were expected over the westcentral and northwest Bay of Bengal until the evening of September 24 before gradually improving.
Fishermen have been advised not to venture into the deep sea until September 25. In north Bengal, Darjeeling, Jalpaiguri and Alipurduar were forecast to receive heavy to very heavy rain on Thursday and Friday.
The system began as a cyclonic circulation over Thailand on September 19 and emerged over the north Andaman Sea a day later. It subsequently developed into a low-pressure area, a well-marked low, a depression and then a deep depression as it moved northwestwards.
The Met officials cited in the report said strong wind shear, associated with active monsoon currents over the sea, was preventing further sustained intensification. The intensity of rainfall in south Bengal is expected to decline from Saturday, while sea conditions are forecast to improve after September 24 evening.
