The low-pressure area over the South-West Bay of Bengal, which has been shifting its bearing to the north and south, is now located off the coast of Sri Lanka, an India Met Department (IMD) update said.
It is expected to become more 'marked' (intensification by a round to being 'well-marked') later today, and could soon start moving back to the north.
NO FOLLOW-UP 'LOW'
A significant development is that a follow-up low-pressure area, which was expected to spin up over the Andaman Sea by tomorrow, may not materialise.
A preparatory circulation is visible over the Gulf of Thailand in this morning's satellite pictures, but this is seen as losing its momentum as it tries to move across South Thailand to the Andaman Sea.
This would leave the Bay of Bengal with just the 'low' currently off Sri Lanka, which, after intensifying a round or two, could end up in a flurry of rain over the South Andhra Pradesh coast.
But, importantly, global model forecasts as well those by the IMD point to an alternative scenario wherein a rain wave heads west from Chennai to the interior peninsula towards the Karnataka coast.
RAIN FOR INTERIOR
This would apparently be masterminded by the 'low' in association with the long trunk of a western disturbance that dips in from North-West India towards the peninsula.
Some models see the possibility of a 'low' being formed in the process over the peninsula, although the IMD does not fancy anything beyond a rudimentary circulation in the making here.
It would drop rain over South Interior Karnataka, parts of Rayalaseema and North Interior Karnataka, coastal Karnataka and southern parts of Goa.
The models are of the view that the Bay of Bengal would need to wait for another eight to 10 days before the next rain-friendly 'trough' or 'low' can form.
As for today, the IMD has forecast heavy rain at isolated places over Tamil Nadu, Puducherry and South Coastal Andhra Pradesh.