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The India Met Department (IMD) has said that this morning's depression over the South-West Arabian Sea has intensified into a deep depression and could develop even further. The IMD expects the fast-evolving weather system to become a destructive very severe cyclonic storm, taking it to just below super cyclone status, as early as day after tomorrow.
The system lay 520 km to the South-East of Socotra Islands (off the Gulf of Aden) and 930 km South-South-East of Salalah, in Oman.
Its evolution as a cyclone should take place by tomorrow and into a severe cyclonic storm in the subsequent 24 hours.
The very warm waters and friendly atmospheric features drive it further in strength to a very severe cyclone, headed for South Oman-South-East Yemen coasts by Saturday.
As the system is expected to move away from the Indian coast, no adverse weather is expected along and off the west coast of India, the IMD clarified.
It issued a warning of squally winds with speeds reaching 55- 65 km/hr and gusting to 75 km/hr over the South-West Arabian Sea this afternoon and gradual increase thereafter.
SQUALLY WINDS
It could assume gale wind speeds of 65-75 km/hr gusting to 85 km/hr by the evening. Squally winds speeding to 45-55 km/hr and gusting to 65 km/hr is likely tomorrow morning.
The wind speed will gradually increase over these regions with the increase in intensity of the system from today until Saturday.
The sea condition will be 'very rough' over the southern-most Arabian Sea during the afternoon and will become 'high' by the evening. It will be 'high' and then 'very high' until Saturday.
Fishermen are advised not to venture into into West-Central and adjoining South-West Arabian Sea from tomorrrow.
Prevailing sea and atmospheric conditions are just right for the intensification of the cyclone, according to an assessment of the US Joint Typhoon Warning Centre.
Sea-surface temperatures are above 31 deg Celsius, which provides sufficient fuel through convection and cloud-building at the ground level.
LOW WIND SHEAR
The vertical wind shear values, or the speed at which the winds suddenly change direction and speed within the system, are currently low or within manageable limits.
High wind shear values, as are typical of a full-fledged monsoon, don't allow the critical storm tower to grow into the desired height that decides its strength and intensity.
This is why cyclones form mostly during the run-up to the monsoon or just after it has withdrawn, and not mid-way through.
Activity in the Arabian Sea has been peaking under the benign watch of a Madden-Julian Oscillation (MJO) wave that moves from West to East periodically over Indian Ocean.
Model forecasts indicate that the MJO wave would be active until June 4, progressively triggering activity in the Bay of Bengal to keep the progress of monsoon on an even keel.
The MJO wave in the heights of the atmosphere packs convection, clouds and heavy rain and underwrites the onset of monsoons and initiates depressions/cyclones on ground.
According to MJO trackers, the current 'wet phase' may last into the first week of June covering the onset phase of the monsoon, as projected by IMD.
BAY WATCH ON
This is precisely why forecasters are looking at the behaviour of circulations over North Tamil Nadu and off Sri Lanka for signs of further development.
An IMD assessment indicates that they would merge and set up a depression, if not a cyclone, tracking along the East Coast towards Kolkata/Bangladesh.
This outlook has found consensus with other models, which, if proven true, would make up for the early loss of traction that the monsoon has suffered thanks to the Arabian Sea cyclones.
The IMD has already forecast heavy rain for parts of Tamil Nadu and Karnataka over the next three to four days in the context of the buzz developing in the Bay.
Monsoon flows this morning are seen directed into the Bay through two different corridors to the North and South of the Maldives and across Sri Lanka.
These are away from the sphere of disruptive influence of the brewing Arabian Sea cyclone, and they should manage to mostly hold out as the Bay gets into the stride.
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