Vanakkam! A partly cloudy, mostly sunny day with light rain is likely in some parts of Chennai city.
This is more or less the consensus outlook of the Chennai Met Office of the India Meteorological Department (IMD) as well as private weather forecasters, domestic and international.
At 8.30 AM, the temperature was 29.9 Degree Celsius and the dew point, 29.4 Degree Celsius. This took down the humidity level from the maximum of 100 per cent to 98 per cent.
The dew point is the temperature at which the air can no longer hold all of the water vapour mixed with it, and some of the water vapour must condense into liquid water. The dew point is always lower than (or equal to) the air temperature.
If the air temperature cools to the dew point, or if the dew point rises to equal the air temperature, then dew, fog or clouds begin to form. It is at this point where the dew point temperature equals the air temperature, the relative humidity is 100 per cent.
If there is a further cooling of the air, say, because the air parcel is rising to higher (and thus colder) levels in the atmosphere, even more water vapour must condense as additional dew, fog, or cloud, so that the dew point temperature then falls along with the air temperature.
This is how precipitation forms…when water vapour is removed from the air so rapidly that the liquid water drops grow to a size where they fall out of the cloud.
The nearest to where this happened early in the morning was off the coast of Puducherry at 5:50 AM, says RainViewer.
So much so, that Chennai bloggers have had to venture further South to Sri Lanka to get the best shot of the North-East monsoon in play during the day, as @ChennaiRains reports:
As for the day today, domestic private forecaster Skymet said it would be mostly sunny with sparse clouding and elevated levels of humidity. Hot and humid!
Partly cloudy (feels like 33 degrees Celsius) with helpful north-easterly winds was the update at 7:30 AM from Weather.com, an IBM business, with not much of a change in the outlook for the rest of the day.
A mostly sunny day with 20 per cent cloud cover, northerly winds, temperature at 32 degrees Celsius (real feel of 37 degrees Celsius as early as 7:43 AM) was the update/outlook from AccuWeather.
Partly cloudy at 7:46 AM; temperature at 27 degrees Celsius (real feel 31 degrees Celsius); humidity at 94 per cent; and winds westerly-south-westerly — just shows how the winds are wavering, as picked by models within a few minutes of each other — and a mostly sunny outlook for the day marked by numerous thunderstorms, says WeatherBug.
All of which led @chennaiweather to tweet the following:
Meanwhile, international weather models have suggested that the most productive week for this month will be November 9 to 15. Here’s the outlook from the Climate Forecast System model of the US:
This is, in turn, based on the outlook for a low-pressure area (likely intensifying into a depression) developing over the Andaman Sea (South-East Bay of Bengal) with a track not yet clear (see projected graphic below showing its likely position on November 5).
It could head anywhere in an arc from North Tamil Nadu to Andhra Pradesh, Odisha and Bengal.