Is the North-East monsoon headed for a washout?

All available indications now point to the washout of the North-East monsoon in the Peninsula, after the drubbing it received during the preceding South-West monsoon.

With half of November gone and no prospects of any major pick-up in rain during the rest of the month, there is little that the last month of December can possibly bring in.

What looked a like a brief revival in activity early this week is proving a non-starter already. Parts of interior Tamil Nadu received heavy rainfall during the 24 hours ending Monday morning but indications now suggest this may not last for long.

Negative IOD

According to India Met Department (IMD), the North-East monsoon is likely to extend its deficient run for next three days thanks to misdirected weather systems in the Bay of Bengal/Indian Ocean.

This is in turn attributable to the persisting negative phase of the Indian Ocean Dipole (IOD), which causes the Indian Ocean just south to Bay of Bengal to warm up abnormally.

This has direct implications for the North-East monsoon, since the warmth builds up lower pressure over the Indian Ocean where most of the moisture gets directed.

The Australian Bureau of Meteorology had earlier said that negative IOD values were at the highest during a 50-year-period, although they have scaled down in recent times.

But the damage has already been done. While the negative IOD is widely thought to have interfered with the proper play-out of the South-West monsoon, it has had a more direct and immediate impact on the North-East monsoon.

The rain deficits built so far during October to November alone tell the story. According to the IMD, the South Peninsula housing the ‘command area’ of the North-East monsoon, has recorded a deficit of 66 per cent until November 9. The worst-hit has been Rayalaseema (89 per cent) followed closely by South Interior Karnataka (84 per cent). Those making the tail are North Interior Karnataka (76 per cent); Coastal Andhra Pradesh (71 per cent); Tamil Nadu and Puducherry (66 per cent); Lakshadweep (63 per cent); Coastal Karnataka (61 per cent); and Kerala (59 per cent).

Poor outlook

The prospects do not look none-too-bright either, according to forecasts. They show residual buzz in the seas surrounding the Sumatra Island, and along a westward course to Sri Lanka, but missing most of Tamil Nadu.

This state of affairs is likely to continue into the last week of the month, with most models favouring southern Tamil Nadu and adjoining Kerala with prospects of receiving spill-over rains from the activity around Sri Lanka and neighbourhood.

As for the rest of the South Peninsula, it looks like a dry patch for the rest of the month unless the South China Sea/North-West Pacific can touch off activity in the Central Bay of Bengal in the near term.

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