The depression over south-west Bay of Bengal has intensified into a deep depression, leaving enough time and space over the next two days for it to ramp up as a tropical cyclone. This will be the second cyclone over the Bay basin during the ongoing north-east monsoon, a month after severe cyclone Dana careened away off the Tamil Nadu towards Odisha-West Bengal.
India Meteorological Department (IMD) said in an afternoon update on Tuesday the deep depression, next only to the status of a cyclone, waited over the south-west Bay at a location about 310 km south-east off Trincomalee in Sri Lanka; 590 km south-southeast of Nagapattinam; 710 km south-southeast of Puducherry; and 800 km south-southeast of Chennai.
The deep depression may continue to north-northwestwards and intensify into a cyclone by Wednesday even as it continues to move to the north-northwest towards the Tamil Nadu coast during subsequent two days, while skirting Sri Lanka coast. The cyclone is expected to be named Fengal, according to the protocol made applicable for the Indian Ocean region.
Heavy rain forecast
The IMD has forecast isolated heavy to very heavy rain at a few places with extremely heavy fall at isolated places over coastal Tamil Nadu & Puducherry on Wednesday; heavy to very heavy rain at isolated places on Thursday; and heavy rain at Isolated places on Saturday and Sunday. Heavy to very heavy rain has been warned of also at isolated places over Coastal Andhra Pradesh & Yanam and Rayalaseema for three days from Thursday to Saturday.
Heavy rain is likely at isolated places over Kerala & Mahe on Wednesday; and over Coastal Andhra Pradesh & Yanam and Rayalaseema from from Tuesday for almost a week until Monday next. Heavy rain is also forecast over Nagaland, Manipur, Mizoram & Tripura on Thursday from outer rain bands that get directed to east-northeast under the influence of a passing western disturbance across North-West, East and North-East India during the next three to four days.
Evening satellite pictures
Evening satellite pictures on Tuesday showed a cloud/rain cover approaching to breach the Chennai coast in Tamil Nadu, and onward south to Thiruporur, Thirukazhukundram, Maduranthakam, Marakkanam, and further towards the south over Nagapattinam, Vedaranyam, Mannargudi and Pattukottai. In interior south Tamil Nadu, clouds hung over Manapparai, Aruppukottai, Sattur, Kovilpatti, Vliattkkulam, Akalakkad, Panagudi and Kuzhithura.
Inbound western disturbance
Passing of a western disturbance over north-west India with an accompanying band of stronger westerlies blowing deep down over east-central India may likely influence the movement/track of the cyclone. The slightly lower but supportive sea-surface temperatures near the coast is more or less neutralised by the growingly unfavourable wind shear values in the higher levels of the atmosphere, which will cause the cyclone to stall off the Chennai coast without crossing it
May loiter the waters
Numerical models predict the system may toy with north Tamil Nadu coast not far from Chennai, without crossing it. It may loiter over the waters, weakened over time as a depression or a low-pressure area, but may refuse to venture back to the outer seas. Numerical models said the weakened system may instead head back to the Sri Lanka-South Tamil Nadu coast by December 6.