New Low-Pressure System Forms Over Bay of Bengal as Cyclone Arnab Weakens Inland

A fresh weather system has developed over the Bay of Bengal as the remnants of very severe cyclone “Arnab” continue to move inland and weaken, the India Meteorological Department (IMD) said on Thursday.

The new system, currently located over the South Andaman Sea near the Andaman and Nicobar Islands, has intensified from a cyclonic circulation into a low-pressure area. Meteorologists expect it to move west-northwestwards and strengthen further over the next 72 hours.

“A cyclonic circulation over the South Andaman Sea has intensified into a low-pressure system in the early hours of Thursday. It is very likely to move in a west-northwest direction and intensify further into a well-marked low pressure over the Andaman Sea and the area adjoining the Andaman and Nicobar Islands during the next 72 hours,” HR Biswas, a senior IMD scientist in Kolkata, said.

However, the weather agency has not yet forecast whether the system will develop into a cyclone or established its likely trajectory. No cyclone warning has been issued so far.

IMD monitors possible intensification

Weather systems over the Bay of Bengal can strengthen through several stages, from low-pressure areas and depressions to tropical cyclones, depending on atmospheric and oceanic conditions.

The IMD classifies these systems according to their maximum sustained wind speeds:

• Low-pressure area: Winds below 31 kmph.
• Depression: Winds of 31–49 kmph.
• Deep depression: Winds of 50–61 kmph.
• Cyclone: Winds of 62–88 kmph.
• Severe cyclone: Winds of 89–117 kmph.
• Very severe cyclone: Winds of 118–166 kmph.
• Extremely severe cyclone: Winds of 167–221 kmph.
• Super cyclone: Winds exceeding 222 kmph.

The new system’s development will be monitored over the coming days to determine whether it strengthens further.

Improved cyclone forecasting capabilities

The IMD uses numerical weather prediction models, multi-model ensembles and advanced data assimilation techniques to forecast cyclones and issue warnings. Its monitoring network includes satellites, Doppler Weather Radars, ocean buoys and coastal observation stations.

According to the department, forecast accuracy between 2023 and 2025 improved compared with the 2020–2022 period. Accuracy gains for cyclone track, intensity and landfall location ranged from 15–45%, 15–35% and 10–30%, respectively, for forecasts extending up to four days.

India’s pre-monsoon cyclone season typically falls in April and May, while October and November are associated with the post-monsoon cyclone season. Weather systems developing during these periods can intensify under favourable conditions.

Cyclone Arnab weakens over central India

Meanwhile, the remnants of very severe cyclone “Arnab” have weakened into a depression as the system continues to move inland.

At around 8:30 am on Thursday, the remnants were located over southern Chhattisgarh and adjoining southern Odisha, according to the IMD.

The system moved at approximately 18 kmph during the preceding six hours. Officials expected it to move further north and weaken into a well-marked low-pressure area by Thursday evening.

While Arnab continues to lose strength, meteorologists are monitoring the separate system over the South Andaman Sea for signs of further intensification. Its eventual development and movement remain uncertain.