A fresh low-pressure system over the south Andaman Sea is expected to intensify into a depression by Saturday, while the remnants of cyclone Arnab brought rainfall and cloudy skies to Kolkata, Howrah and adjoining districts of south Bengal on Thursday.
According to weather department officials quoted by The Statesman, the new system is likely to move west-northwestwards and develop into a well-marked low-pressure area over the south Andaman Sea and adjoining Andaman and Nicobar Islands by Friday. Its intensification into a depression is considered certain at this stage, officials said.
Whether the depression will strengthen further into a cyclone remains to be ascertained by the Regional Meteorological Centre. Observations so far indicate that the system may move towards Andhra Pradesh during the later stages of its development, although its eventual track remains under assessment.
The developing system emerged as the region was still experiencing the effects of cyclone Arnab. The very severe cyclonic storm had weakened into a depression, with its remnants lying over south Chhattisgarh and adjoining south Odisha. Those remnants brought morning rainfall to Kolkata, Howrah and other parts of south Bengal on Thursday.
A weather official explained that the rainfall was linked to the changing structure of the cyclone after landfall. While a cyclone generally has concentrated and tightly held cloud bands, its outer-band clouds become looser and more scattered after the system dissipates. These scattered clouds can continue to produce rainfall even after the storm has weakened.
The official also attributed the rainfall to the changing distance between the remnants of Arnab and Gangetic West Bengal. While the cyclone was over the Bay of Bengal, it moved in a relatively straight line. After landfall, however, it turned back and moved perpendicularly across the region towards Chhattisgarh. This reduced its distance from Gangetic West Bengal from more than 700 kilometres to just over 500 kilometres on Thursday.
As south Bengal lay on the periphery of the weakening system, its loose outer clouds contributed to the rainfall and persistent cloud cover across the region. The latest system in the Andaman Sea means that weather conditions over the Bay of Bengal and the east coast will remain under close observation in the coming days.
The Regional Meteorological Centre is expected to assess whether the depression strengthens further and to issue subsequent updates on its movement and possible impact. The immediate forecast milestones are the system’s expected development into a well-marked low-pressure area by Friday and a depression by Saturday.
