India Meteorological Department (IMD) has set up a watch for a remnant cyclonic circulation from the erstwhile South China Sea typhoon ‘Noru’ to reach the Bay of Bengal in the next two days, which coincides with the normal date for the end of the monsoon. But it is more or less clear now that the monsoon will extend at least into the first week of October and delay its withdrawal as the ‘Noru’ remnant crosses the Andhra Pradesh coast and further inland.

‘Noru’ hits Vietnam coast

The remnant cyclonic circulation was seen this (Thursday) morning as a strong circulation fresh on release from the Vietnam coast, where ‘Noru’ made a landfall the previous day. It will lose some intensity after being forced to share flows with another circulation that has persisted over the West-Central Bay over the past few days. The IMD’s numerical projections suggest the weakened remnant will merge into this resident circulation and grow in strength until October 3 or 4, when it will cross the Andhra Pradesh coast.

Track towards North-West

It is forecast to later propel into Central India and North-West India, where it will meet the seasonal anticyclone (high-pressure area) that heralds the withdrawal of the monsoon in its own den over Rajasthan. In this manner, it is expected to disrupt the withdrawal schedule and delay it at least into the first week of October, until when forecasts are available. The US National Centres for Environmental Prediction does not see the monsoon withdrawal resuming at least until mid-October, by when, in the normal course, the stage will have been set for the North-East monsoon over the South Peninsula.

Rain cover for South

Some models point to a gradual build-up of rain cover over the South Peninsula from October 7 to 15. The IMD’s numerical model projections indicate the formation of a trough along the Tamil Nadu coast, with a south-easterly wind component, around this time. But the anticyclone over North-West India will have to establish along specific bearings and latitude, and sustain strong easterly to north-easterly flows for the North-East monsoon to set in over the South Peninsula. The normal window for this is October 18-22.

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