Cyclonic circulations on either side of the peninsula located over Lakshadweep and off coastal Tamil Nadu are currently driving a rain spell over the South Peninsula.
The two have combined to set up 'wind shear zone' of monsoon turbulence to the south of Sri Lanka. The shear zone represents an area where the monsoon is most active.
HUMONGOUS CLOUD
This is apparently what has triggered the formation of the humongous cloud build-up to the south-west over Kerala, covering most of the Maldives and Lankshadweep Islands this morning.
Satellite maps indicate that from its current elevation, the cloud bank is moving towards the southern Kerala coast, stretching from Kollam to Thiruvananthapuram.
It has been raining heavily in Thiruvananthapuram for the last 30 minutes, amidst heavily overcast skies.
A breakaway parcel of cloud is located over Thuckalay, Thengappattanam and Kuzhitturai in extreme South Tamil Nadu and Parassala to south Thiruvananthapuram in Kerala.
Many parts of Kollam and adjoining Pathanamthitta districts in Kerala have been receiving moderate to heavy rain over the past couple of days.
ALERT FOR CHENNAI
The late monsoon surge is a godsend for Kerala, which has witnessed persisting droughts during the last few seasons, endangering power supply systems and even drinking water supplies.
South Interior Karnataka, another Met subdivision suffering from inadequate monsoon showers, has also reported significant gains in the recorded rainfall during the last week.
The south-west monsoon has already delivered surplus rain to Tamil Nadu and Puducherry, which are normally considered rain-shadow regions during June to September.
Tamil Nadu and Puducherry could receive further showers as the current surge of the monsoon brings this Met subdivision also under coverage.
In fact, the circulation now spotted off the Chennai coast, could intensify and move towards the city's coast by September 11 (Monday), bringing in its wake a welter of thundershowers and high winds.