It is ironical that during Peak Northeast Monsoon time the continual discussions among weather bloggers of Chennai has been mostly about pollution with some heated debates on the origins of the current pollution episode at Chennai. At times one wonders whether has Chennai not seen pollution at all earlier and is the current reaction an exaggeration.
After looking at hourly AQI data from the US Consulate Air Quality Monitoring Centre at Gopalapuram it is quiet obvious Chennai’s winter pollution has a close connect with the performance of Northeast Monsoon. 2016 which was one of the worst years along with 2018 saw long periods of unhealthy Air Quality conditions over Chennai. Unfortunately a change in instrumentation last year possibly has meant 2018 November data is not available at US Consulate archives.
The first few days of 2019 is possibly as worse if not much worse than 2016 with nearly 70% of the month seeing AQI values exceed the Unhealthy threshold of 150. Interestingly if one were to observe the wind patterns during these continuous unhealthy air quality episodes more often than not they have coincided with Northerly winds over the Eastern Coast of Peninsular India once again confirming how important the Easterly winds are for keeping pollution under check during the winter months.
The good news is over the next 24 hours or so we will start to see the Easterly winds strengthen over the Bay giving some hope for a return of momentum for NEM 2019. Delta and South TN coastal areas could see the return of weak Easterlies tonight with the winds streamlining from later tomorrow night. Chennai and North TN areas could see the Easterlies return from early Wednesday brining a possible end to the current pollution episode and along with it hope for rains too.
Today we could once again see some rains over the interior parts of Tamil Nadu. In particular places along the Western Ghats are likely to see moderate rains at many places with occasional heavy spells. Kerala could see late evening thunderstorms in many places.
Chennai and rest of coastal Tamil Nadu may need to wait for another day or so before we can start looking to the East with hope.