This is because both depressions are expected to form over the central parts of both the seas
The transformation into a depression has not happened within timelines fixed earlier
It would move away from the West Coast of India
Monsoon depressions are forecast to spin up to either side of the peninsula over both the Arabian Sea and the Bay of Bengal even as the heavy to very heavy rain regime is moving away from the South Peninsula.
This is because both depressions are expected to form over the central parts of both the seas, away from South India, with a western disturbance moving from Afghanistan-Pakistan to North-West India will cast its own impression on these systems.
The India Met Department (IMD) said in the Wednesday morning update that an existing intensified (well-marked) low-pressure area over the central parts of the Arabian Sea is expected to further intensify into a depression by Thursday.
The transformation into a depression has not happened within timelines fixed earlier, and, normally, such postponements indicate a waning confluence in the eventuality. But the IMD has persisted with the outlook for the event, and seems to be supported by global weather models, led by the Climate Prediction Centre (CPC) of the US National Weather Service.
As regards the "broad area of low pressure over the Arabian Sea", the CPC cites GFS (Global Forecast System) and the ECMWF (European Centre for Medium-range Forecasts) models are in excellent agreement that it would develop into a depression, even a cyclone.
It would move away from the West Coast of India while rapidly intensifying as it tracks west across the Arabian Sea. There are increasing chances that this tropical cyclone approaches Oman or Yemen early during the week October 23-November 5.
Based on the predicted evolution of the weather-boosting Madden-Julian Oscillation (MJO) wave, model guidance, and climatology, moderate confidence exists that another depression forms in either the South-West Bay of Bengal as well, the CPS said. ■