The South Peninsula would start witnessing an increase in rainfall activity from October 25 (Wednesday next) in what is likely the final count-down to a delayed arrival of North-East monsoon.
Also called the winter monsoon, rains associated with the season should have started lashing the Tamil Nadu coast during the usual October 15-to-20 window.
But the churn in the Bay of Bengal associated with the depression that made landfall last night over Odisha meant that the flows towards Tamil Nadu were not allowed to settle and organise.
A couple of typhoons (cyclones) in the North-West Pacific/South China Sea too have been distractions. Among these, typhoon Lan, is forecast to hit south Japan and weaken by October 23.
The other is tropical storm of much lesser strength (tropical depression) farther out into the West Pacific, and headed again towards South Japan and seen weakening from October 24.
Once the drag effect from these Pacific systems gets over, the North-East monsoon in the Bay of Bengal should fall into proper place and start impacting the Tamil Nadu coast and neighbourhood.
PILOTING RAINS SEEN
A familiar weather tracker of the US Climate Prediction Centre points to activity building across the Bay and directed towards the Tamil Nadu and Coastal Andhra Pradesh coast by October 24/25.
According to the European Centre for Medium-Range Weather Forecasting, the weakening depression over Odisha would throw down a helpful trough into the Bay to host the North-East monsoon.
This trough would narrow and wrap around the West Coast (Arabian Sea) and the Tamil Nadu coast (Bay of Bengal) by around October 24 likely triggering the piloting rains.
The troughs would gradually expand, and, to the Bay of Bengal side, connect with the Gulf of Thailand to clear the way for rain-friendly 'easterly waves' and other systems to cross into the Bay.
India Met Department projects that organised showers may start hitting the Tamil Nadu coast and the West Coast after October 26.