A storm tracker featured by the US Climate Prediction Centre seems to suggest that an incoming rain-generating system coast could drop anchor off the Tamil Nadu coast for longer than a predecessor did just last week.
This is because of the specific mechanics involved - the system originating from Andaman and Nicobar Islands might split up with one 'cell' careening towards Sri Lanka and the other towards the Tamil Nadu coast.
But both are predicted to meet up and re-consolidate into a single system off the Sri Lanka-Tamil Nadu coast. The combined entity would undergo intensification here and drop anchor there.
Later, it would break up once again with a remnant being led away north-northeast along the Andhra Pradesh-Odisha coast towards Gangetic West Bengal.
The parent is predicted to stay put for days together on or just off the Chennai coast in Tamil Nadu. If this scenario were to pan out, Chennai could be faced with a harrowing time dealing with flooding rain.
The European Centre for Medium-Range Weather Forecasts also hinted twin systems travelling towards the Sri Lanka and Tamil Nadu coasts from this weekend and merging off the coast.
It also indicated the presence of a trough of low pressure - lower in grade than a low-pressure area but capable of sustaining rains - persisting off the Chennai coast up till December 6 up to which forecasts were available.