Constantly shifting meteorological parameters over the South Bay of Bengal are making it very difficult for weather models to put a time frame for development of anticipated weather systems.
Conditions have been made volatile with the arrival of a Madden-Julian Oscillation (MJO) wave over adjoining East Indian Ocean, promising to stir up things even further.
The MJO wave travels periodically in the higher levels of the atmosphere from West to East, over the Indian Ocean from the East African coast to Indonesia, before moving into the Maritime Continent.
The wave packs a heady mixture of high winds and deep clouds and impacts ground-level weather by triggering monsoon onsets, low-pressure areas or setting up storms.
According to global forecasts, the MJO wave would stay active above the Indian Ocean (including South Arabian Sea and South Bay of Bengal) until December 2/3, affecting the South Peninsula also.
This phase could lead to storm formation (a preparatory 'low' is already present in the Bay and another forecast to form by early next week) in the Bay, with extension into the Arabian Sea.
The current 'low' is apparently waiting for a competing system over East Indian Ocean (further South of the Bay) to fade before it can become more 'marked' (intensify).
Slow system movement
Some modes believe that its slow movement would aid intensification over Sri Lanka, the Gulf of Mannar and South Tamil Nadu, before it meanders into the Lakshadweep Sea/South-East Arabian Sea.
It could intensify further there, which puts the southern coasts of both Tamil Nadu and Kerala under the threat of heavy rain early into the new week.
A few other models show the possibility of this weather system being driven North parallel to the West Coast(off Karnataka-Goa) apparently under the influence of an incoming western disturbance.
Meanwhile, eastern parts of the Bay would have burst up with fresh activity as a follow-up 'low' forms which the European Centre for Medium-Term Forecasts could head towards the Tamil Nadu coast.
By the time it reaches the North Tamil Nadu/South Coastal Andhra Pradesh coasts, it would have become at least a depression. Some peer models indicate the possibility of a tropical cyclone here.
With the MJO wave expected to stay active over the next week, forecasters are watching the developments with curiosity.