The remnant, well-marked low-pressure area from erstwhile cyclone Fengal continued to bring heavy to extremely heavy rainfall across parts of north Tamil Nadu, south interior Karnataka and Kerala for the second/ third consecutive day from Monday into Tuesday, indicating a ravenous appetite for moisture from peninsular seas.
The system was located over coastal Karnataka and adjoining east-central Arabian sea on Tuesday morning. It may retain its intensity until Wednesday and weaken thereafter, moving further away from the West Coast.
Heavy to very heavy rain
Heavy to very heavy rain and extremely heavy rain was recorded over Coastal Karnataka and north Kerala during 24 hours ending on Tuesday morning, an India Meteorological Department (IMD) update said. It was heavy to very heavy over north interior Tamil Nadu; and heavy over South Interior Karnataka, Coastal Andhra Pradesh & Yanam; and Rayalaseema.
South Peninsula may continue to witness hit-or-miss thunderstorms from moisture left behind by Fengal remnant. Numerical weather predictions hint at an easterly wave bringing back organised showers for Sri Lanka and south Tamil Nadu next week.
Global model outlook
The European Centre for Medium-Range Weather Forecasts says in its latest outlook most of Tamil Nadu and parts of Kerala may witness showers until December 13. The US Climate Forecasts System concurs, but even looks even beyond to indicate rain into the week that follows (until December 21), a view seconded by US National Centres for Environmental Prediction .
Australian monsoon
It remains to be seen how long easterly waves can sustain since winds may shift direction with Inter Continental Convergence Zone (ITCZ) that tracks the sun, migrates to southern hemisphere sooner than later, signalling an end to north-east monsoon.
It is this movement of ITCZ, a planetary belt of low-pressure, that will up next monsoon event over Indonesia and Australia. Seasonally, it triggers thunderstorms and rain over both Indonesia and northern Australia between November and mid-March as moist west to northwesterly winds blow into monsoon trough to the north of Australia.
MJO moves in time
Monsoon winds are developing over west Indonesia, after rain and storm-driving Madden–Julian Oscillation (MJO) left the Bay of Bengal (where it helped set up cyclone Fengal) and entered the Maritime Continent in Australia’s vicinity. The Australian Bureau of Meteorology said there is currently a minimal chance of monsoonal arrival over northern parts of the country next week.