Weather in Tamil Nadu continues to remain in suppressed mode along with rest of the country with dry weather continuing to dominate across the region. 2016 is turning out to be a year to study for Tropical Meteorologists across the year thanks to the regular pattern being thrown out of the window consistently since mid Summer. By April there was a strong expectation for the El Nino to switch into a La Nina, possibly into one of the strongest in recent times, after so many false starts La Nina conditions started to establish only around September though atmosphere has been switching back to El Nino mode time to time playing truant.
Similarly what should have been straight forward progression of tropical waves like MJO has gone into a complicated stop & go pattern leading to not only Southwest Monsoon seeing erratic rainfall pattern the same is now visible in Northeast Monsoon as well. While going by numbers MJO is supposedly in North Indian Ocean since the last couple of days though going by convection the impact seems to be very limited. We would possibly see some studies being taken up in the days to come on why 2016 behaved strangely.
If one compares the satellite maps between 2016 and 2015 one can clearly observe the convection in 2016 has been staying much South compared to 2015 leading to dry weather in Tamil Nadu except for extreme South TN and adjoining Sri Lanka.
With Intertropical Convection Zone (ITCZ), the powerhouse for monsoon rains in the tropical regions like Indian Sub Continent, staying very close to the Equator the convection and rain bands are also staying in the lower latitudes while High Pressure dominates possibly from 12 / 13 N latitude (roughly Chennai Latitude). This dominance of High Pressure is indicated by the cooler winter like conditions as well thanks to the dry atmospheric conditions.
Since November 1st week pretty much there has been no tropical disturbance in the North Indian Ocean to drag back the ITCZ up north slightly for the monsoon conditions to improve. One could be mistaken the summer chart as Northeast Monsoon day considering how optimistic the satellite image looks like. It pretty much sumps up the influence a tropical disturbance could play in creating convection. With no tropical disturbance since November 7th slowly the ITCZ has drifted down following the Sun towards Southern Hemisphere.
Until such time a tropical disturbance develops and moves up the latitude convection & rain bands will remain lower in latitudes. As days progress the ITCZ gets firmly established in Southern Hemisphere indicating the end to our monsoon season. So the immediate priority for the monsoon to kickstart over most parts of Tamil Nadu is a strong tropical disturbance that climbs up the latitude. Till then Weather in Tamil Nadu is bound to be under suppressed conditions.