A deep depression on the Bay of Bengal intensified into Cyclone Montha late on Sunday night, barrelling towards Andhra Pradesh, where it is expected to make landfall on Tuesday night.
Post landfall, the storm will have more impact in north Bengal than in the south, said Met officials.
While heavy rain is expected in some districts of south Bengal, very heavy rain is likely in north Bengal, according to the Met forecast. There is an orange warning for north Bengal on October 31 (Friday), the second most serious warning, implying “be prepared to take action”.
In Calcutta, cloudy sky and light to moderate rain are expected between Tuesday night and Friday morning, said a Met official.
After landfall, the storm will move north-northwest, according to a projected track in the Met bulletin issued on Monday. As it moves through Andhra, Odisha and Chhattisgarh, the storm will keep losing momentum.
According to the projected track, by Wednesday morning, it will weaken into a deep depression over Chhattisgarh.
“From a depression, it will weaken into a low-pressure area and then a cyclonic circulation. But as it moves north, Jharkhand, Bihar and Uttar Pradesh may come under its direct area of influence. In that case, a lot of moisture incursion will happen in Bengal, the bulk of it in north Bengal, which borders Bihar,” said a Met official in Calcutta.
Montha was over the southwest and adjoining west-central Bay of Bengal on Monday morning. Around 11.30am, moving at 17kmph, the storm was 530km from Kakinada in Andhra Pradesh, where it is expected to land on Tuesday night.
It is likely to move north-northwestwards and intensify into a severe cyclonic storm by Tuesday morning, unleashing a peak wind speed of 110kmph. It is tipped to maintain that momentum at the time of landfall.
“Continuing to move further north-northwestwards, it is very likely to cross Andhra Pradesh coast between Machilipatnam and Kalingapatnam around Kakinada during the evening/night of 28th October as a severe cyclonic storm with a maximum sustained wind speed of 90-100kmph gusting to 110kmph,” said a Met bulletin.
On Tuesday, heavy rain is expected in South 24-Parganas and East Midnapore. Thunderstorms with gusty wind (30-40kmph) and lightning are likely in Calcutta, North and South 24-Parganas, East and West Midnapore, Hooghly, Howrah, and Jhargram districts of south Bengal.
On Wednesday, heavy rain is likely in North and South 24-Parganas, East & West Midnapore and Jhargram. Thunderstorms with gusty wind (30-40kmph) and lightning are expected across south Bengal.
On Thursday, light to moderate rain or thundershowers are likely across south Bengal. Purulia, East and West Burdwan, Birbhum and Murshidabad may get heavy rain.
On Friday, light to moderate rain or thundershowers are likely across south Bengal, with heavy rain expected in Birbhum and Murshidabad.
North Bengal will be rainy between Wednesday and Saturday. On Thursday, heavy rain is likely in Darjeeling, Kalimpong, Jalpaiguri, Malda and North Dinajpur.
On Friday, “heavy to very heavy (7 to 20mm)” rain is likely in Darjeeling, Kalimpong, Jalpaiguri, Cooch Behar and Alipurduar districts.
Fishermen have been advised not to venture into the sea along and off the Bengal coast from October 28 to 30.