A cyclone forming over the Bay of Bengal could intensify into a severe cyclonic storm by Wednesday, bringing rain and gusty winds to Kolkata and several districts of south Bengal, according to the Alipore weather office. The system is expected to develop from a depression in the south-eastern Bay of Bengal and move gradually north-westwards.
The depression became more clearly organised on Saturday, with an associated cyclonic circulation extending up to 7.6 kilometres above sea level. It is forecast to strengthen into a deep depression on Sunday and become a cyclonic storm by Monday evening over the central parts of the southern and adjoining west-central Bay of Bengal.
The system could continue gaining strength as it moves north-westwards. Weather officials have indicated that wind speeds may reach 40 to 55 kilometres per hour when the depression forms and 50 to 60 kilometres per hour after it intensifies into a deep depression. Once it becomes a cyclone, winds could increase to between 60 and 85 kilometres per hour. If it develops into a severe cyclonic storm, sustained winds over the sea may reach 85 to 95 kilometres per hour, with gusts of up to 105 kilometres per hour.
Kolkata is expected to begin receiving rain from Wednesday, with showers continuing at least until Saturday. The city may experience thunderstorms and gusty winds of 30 to 40 kilometres per hour, while wind speeds in some areas could reach 40 to 50 kilometres per hour. Although heavy rain is not currently expected in Kolkata, the combination of rain and strong winds could affect road conditions, local drainage and movement across the city.
The heaviest rainfall alert covers South 24 Parganas and East Midnapore, where 7 to 11 centimetres of rain may occur from Thursday to Saturday. Howrah, Jhargram and West Midnapore are forecast to receive heavy rain on Friday and Saturday. The forecast covers much of south Bengal, though the intensity will vary between districts.
No warning has so far been issued for fishermen at sea, according to the weather office. The developing system is not expected to affect north Bengal. Darjeeling, Kalimpong, Jalpaiguri and Alipurduar are likely to remain mainly dry, apart from the possibility of isolated rain in Darjeeling and Kalimpong on Sunday and Monday. Dry weather is expected across the northern districts thereafter.
Temperatures in south Bengal are expected to remain largely unchanged for the next three days before rising by two to three degrees over the following two days. Kolkata recorded a minimum temperature of 21.7 degrees Celsius on Sunday morning, 1.4 degrees above normal. The city’s maximum temperature on Saturday was 29 degrees Celsius, 1.6 degrees below normal. The weather office’s next updates will determine whether additional warnings are issued for coastal districts, fishermen and urban areas as the system strengthens.
