An experimental US ocean forecast model has hinted that the Arabian Sea might whip up some action around May 25.
It is forecast to take place in the east-central and adjoining east Arabian Sea (north of the Lakshadweep islands) oriented in a west-to-east trajectory.
The west-to-east orientation would seem to rule out an away-going system that causes incoming monsoon winds to falter and unsettle a concurrent monsoon.
Such away-going systems have triggered the formation of rogue weather systems in both the Arabian Sea and the Bay of Bengal during the onset period in the past, diverting precious moisture and rains away from mainland India.
The US model suggests that the activity in the Arabian Sea would peak around May 25 before petering out over the next two days, likely after ‘transferring the energy' to the west coast of India.
But meteorologists are of the view that it is too early still to take a call on the onset of monsoon, although the emerging pattern from the May 17 as depicted by various models is strikingly similar.
The US National Centres for Environmental Prediction (NCEP) has retained the outlook that the Arabian Sea shake-up could be preceded by similar activity in the Bay of Bengal during May 12 to 20.
On Tuesday, India Meteorological Department (IMD) traced out a crucial north-south trough running all the way down from Bihar to southwest Bay of Bengal.
This would be monitored for any signs of triggering activity in the Bay.
The NCEP sees the weather system developing over south-central and adjoining southwest Bay of Bengal, tracking southwest to hit Sri Lanka first and Kerala later.
Wet MJO phase
The European Centre for Medium-Range Weather Forecasts (ECMWF) is of the view that southeast Arabian Sea would get impacted by a weather-driving wet phase of a Madden-Julian Oscillation (MJO) wave from May 12.
MJO wave travels periodically from west to east in the higher levels and can set up weather on ground in the form of monsoon onsets, low-pressure areas and even cyclones.
The alternating dry phase has been blamed for ‘break-monsoon' and other forms of interferences that give rise to intra-season droughts during monsoon.
Meanwhile, heating of the land over northwest India, crucial for setting up the monsoon-driving temperature and pressure gradients, was apace during the 24 hours ending Tuesday morning.
The ECMWF is of the view that concentrated heating would engulf west and southwest Rajasthan and adjoining south and East Pakistan from May 14.
An IMD update said that heat wave conditions have developed over some parts of Rajasthan overnight on Tuesday. The highest maximum temperature of 45.6 deg Celsius was recorded at Barmer.
Still, it maintained the outlook for the arrival of a fresh western disturbance, with its calming impact on heat, over the next few days.
The system will affect western Himalayan region and even the adjoining plains of northwest India from Wednesday.
Satellite imagery revealed the presence of convective (thundershower-causing) clouds over parts of Arunachal Pradesh and southeast and central Bay of Bengal. Low to medium clouds (partly clouded conditions) were seen over parts of the Andaman Sea, and central, east, northeast and peninsular India.
Weather-making troughs tracked south-southeast down from Bihar to Assam across sub Himalayan West Bengal. Another trough ran north-south from Bihar to south west Bay of Bengal across Jharkhand, Orissa and west central Bay of Bengal.
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