Parts of Chennai were blessed with unexpected showers yesterday (Saturday), in the afternoon. Unfortunately, they do not seem to have done enough to wash the air entirely clean of pollutants. Here's a look at the National Air Quality Index maintained by the Central Pollution Control Board.
Despite the sharp thundershowers in some areas of the city, the air quality index continued to take a knock in the morning, with Velachery recording a PM2.5 score (particulate matter of less than 2.5 microns) of 254 (poor) while Alandur Bus Depot was at 249 (poor) this Sunday morning.
The extent of pollution was lower (and therefore better) at Manali Village (185, moderate) while no data was available with respect to Manali in the city, which had returned some of the worst readings over the past few days.
In comparison, pollution levels had come down markedly in Bengaluru (mostly in the green, and satisfactory) though some poor levels continue to be reported from Hyderabad.
Enabling weather trends
So, what could be the trend of enabling weather factors for Chennai today? Especially, with the once-mighty Cyclone Bulbul having blown over and faded far out to the East-North-East across the Sunderbans and adjoining Bangladesh?
According to the Chennai Met Office of India Meteorological Department, city can expect westerly to north-westerly winds at 4.3 km/hr; temperature and dew point temperature locked at 27.5 degrees Celsius each; humidity at the maximum of 100 per cent under partly cloudy conditions at 5.30 am..
RainViewer has reported early morning showers from places North of Chennai — across the Mettu-Naidupetta-Sullurpetta-Varadiahpalem-Gummidipoondi belt — as well as Avadi-Ramapuram-Sriperumbudur to its South.
Change in wind direction?
According to Weather.com, an IBM Business, and WeatherBug, the winds might change course to being seasonal and weather-friendly easterly to north-easterly as the day (Sunday) wears on.
It should also be remembered that Chennai, being a coastal area, witnesses high evaporation from the neighbouring seas (Bay of Bengal). When the wind blows from the sea to land, it carries moisture.
When the moist air mass impacts hills closer to the coast, or get lifted up through other means (inherent convection), this can cause rainfall. These rains occur mostly during the day, and cannot be accurately predicted.