Northeast Monsoon Winds Down in North Tamil Nadu

After providing historical rains more than once Northeast Monsoon has wound down over North Tamil Nadu.  While officially the season ends on December 31st it is fair to assume looking at the model outputs over the next week or so the Northeast Monsoon rains are pretty much over for North Tamil Nadu this year.

In a year characterized by high intensity spells that created the fear of rains over most people of Chennai, the city has not seen dry days stretch to about 15 days since 8th December.  Except for some isolated rains in North TN during this period most of the rains have been happening over South Tamil Nadu. Since the season started officially on October 1st for the first time we have seen the Daily Rainfall Graph record no rains yesterday and is likely to be repeated today as well. Capture

With North Tamil Nadu already going through a dry patch let us look at what is in store over the next few days.  Going by the Total Precipitable Water which is an indicator of the likely possibility of rains, higher the value better the rainfall prospects, we can see Bay is going to be fairly dry for the next week or so.  23_12_1

When one looks the above map in sync with the possible Inter Tropical Convergence Zone (ITCZ)  location it is quite clear the convection has moved South of Equator.  ITCZ is the primary factor that drives the rainfall over the tropics.  This region of convection follows the sun moving between Tropics of Southern Hemisphere & Northern Hemisphere.  During the summer of Southern Hemisphere the ITCZ is normally found South of Equator coinciding with the Australian Monsoon Season while during the Northern Hemisphere Summer it is found north of Equator coinciding with the Southwest Monsoon season of India.


Going by the surface wind patterns and clouding pattern it is quite clear while parts of Maritime continent (Indonesia / South China Sea Region) still is seeing the ITCZ straddling on either side of the equator over the Indian Ocean the ITCZ has moved South of Equator which is an indicator of the coming to an end of the Northeast Monsoon in all probability.

Finally when one sees the Precipitation accumulation chart for the next few days it is fairly clear the rainfall prospects are not anything extra ordinary with some rains seen over parts of Coastal South TN.


While we are not the official forecasting agency it is fair to say as far as we are concerned it is curtains for Northeast Monsoon over North Tamil Nadu.  Except for some isolated showers which could possibly be passing showers at most places we are not going to see any organized rain activity again for this region as 2015 winds down.