It is an understatement if one remarks Northeast Monsoon is called as a poor cousin of Southwest Monsoon. Nowhere this difference is more visible than among the research community where Northeast Monsoon as a phenomenon is less popular in terms of research studies. Not only is NEM less popular among the research community for many years even with official weather agencies NEM was many times treated as an after thought. It is only recently we have started seeing NEM specific long term weather outlooks rather than a generic winter rainfall outlook. It is worth mentioning here unlike Southwest Monsoon which has clearly defined protocols with regard to onset & withdrawals there are no strict protocols for Northeast Monsoon with often things decided based on human inference.
It is in this context one has to see withdrawal of Northeast Monsoon because there are certain indicators which provide for cues on what is likely to be ahead of us in terms of the Monsoon Prospects. As we get to the second half of December a few seasonal indicators provide these cues for withdrawal of Northeast Monsoon. Break in rains during December alone could not be considered as possible withdrawal indications as one can always argue breaks are not uncommon even during the month of December. One such indicator is the presence of High Pressure Zones over Central India which brings the drier Continental winds from North on a more consistent basis. This anti cyclone over Central India is also an indicator of strengthening winter conditions over the Indian Sub Continent.
While the next 10 days or so from later this week promises to be dry for most of Tamil Nadu indications are we might see some rains during the 1st half of January though the rains will possibly stick to south of 12N latitude rather than bringing wide spread rains over the state. Similarly the presence of strong High Pressure Zone over the Peninsular India also brings about a different dynamic as well to the weather equation. Any pulse / disturbance in Bay will struggle to move WNW & instead will struggle to intensify under weak steering conditions & move towards the Indo China Peninsula thereby reducing the rainfall over Peninsular India.
All in all while it may not be time yet to say Northeast Monsoon has withdrawn completely but it has started to bid adieu from North Tamil Nadu & South Andhra Pradesh. We may have to wait and see for another week or so to understand if the upcoming break in rains extends long enough to realize NEM is possibly saying Good Bye to places in Delta dts & South TN as well. In the meanwhile today we may see moderate rains in a few places between Pondicherry & Delta dts while tomorrow there could be some rains in Delta dts. The pattern being rain bands gradually shifting south before completely stopping towards the end of this week.