The Hindu Business Line : `Low' advantage forfeited as rains drive north-east

According to an India Meteorological Department (IMD) update, the `low' may already have been appropriated by a north-south trough and led to its weakening.

TROUGH PRESENT

The IMD on Thursday evening detected the presence of this trough with merely an embedded cyclonic circulation over northeast Bay of Bengal and neighbourhood.

The system is forecast to bring in a fresh round of fairly widespread to scattered rainfall over the north-eastern States during next 24 hours and isolated thereafter.

Now, this can only hold up the withdrawal of the south-west monsoon on retreat, delaying the arrival of its northeast counterpart or the winter monsoon over the peninsula.

Isolated to scattered rainfall activity has been forecast over extreme south peninsula during the next three days in what is identified as `withdrawal symptoms' associated with the south-west monsoon.

The humidity levels would have come down to much lower levels and the skies stay clear for four to five days at a stretch before the south-west monsoon could be considered as having withdrawn.

Meanwhile, the pan-ocean trough linking the Bay of Bengal, the South China Sea and the west Pacific was evident on Thursday jointly held to place by a `low' each in all seas.

NEXT WINDOW

With the latest `low' having been accounted for by the north-south trough, the Bay would need to look for the next `window' for precipitating the north-east monsoon.

No model indicated the formation of a helpful circulation, though the Fleet Numerical Meteorology and Oceanography Centre of the US Navy expected the Bay circulation to track towards Sri Lanka, only to be stymied by opposing flows from the north-west.

The IMD streamline graphics on Thursday showed no evidence of the south-westerly flows over the peninsula; in fact, weak north-easterlies were on display, presumably not strong to trigger seasonal rains.

The IMD maintained the outlook for the arrival of a feeble western disturbance across the Western Himalayan region during the next three days.

On Thursday, the minimum temperatures were above normal by 3 to 4 deg Celsius over Rajasthan and Madhya Pradesh. They are below normal by 2 to 3 deg Celsius over parts of Indo-Gangetic plains.

Forecast

No significant change in minimum temperatures is being forecast during the next two days but they are likely to fall thereafter. Satellite pictures showed convective clouds over parts of north Bay of Bengal.

An update from the Regional Met Centre, Chennai, said that rainfall was reported from a few places over interior Tamil Nadu and Kerala during the 24 hours ending Thursday morning. Isolated rainfall occurred over coastal Tamil Nadu, coastal and south interior Karnataka.

Forecast for the next two days said that rain or thundershowers are likely at a few places over Kerala, Tamil Nadu, Puducherry, coastal and south interior Karnataka.

Isolated rain or thundershowers are likely to occur over Lakshadweep, Andhra Pradesh and north interior Karnataka.

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