There’s always a silver lining when it comes to rains

As far as Chennai is concerned, Between October 1 and November end, Nungambakkam recorded 72.9 mm of rainfall, which amounts to a deficit of 605.8 mm. Similarly, in Meenambakkam, we have seen 63.1 mm of rains, which is a deficit of 551.7 mm. Some people have called it a pathetic situation. Fortunately, there are signs of formation of two systems. The first one is definitely likely to result in rainfall in a day and by Thursday night, we can expect fairly good rainfall, lasting for three to four days along coastal Tamil Nadu. A second system is expected to enter around December 4, from the Malaysian side. It is likely to move towards the western side, which is good for Tamil Nadu. On occasions, such systems are known to turn west, and again turn north, which means the rain bearing clouds would move away from Tamil Nadu. 

However, rainfall pattern is a very interesting phenomenon. For example, the first system (likely to result in rains from December 1) is expected to bring rains across Tamil Nadu but how much rains each pocket gets will change according to prevailing winds and various other factors. However, will the two systems—providing they move in the correct direction- wipe out the existing deficit is a huge question. Currently, the way things are, only a rainfall that is three times normal in quantum for the month of December can wipe out the deficit. (there is an annual normal, seasonal and monthly normal). The deficit is more since there has been hardly any rainfall in October and November this year. In the past, we have had occasions when rains have been poor or marginal in October, but a heavy rainfall in the succeeding month has helped narrow the deficit or wipe it out entirely. Unless there is a torrential downpour in December this year, there could still be a deficit. There are also some concerns over the onset of cold weather over the state in the last couple of days. At 20, Chennai’s minimum temperature was two degrees below normal. 

Tirupattur recorded 15, which is four degrees below normal. However, the prevailing cold weather, caused by the presence of more northerly winds and less easterly winds,  can be broken by rainfall. Thus the fear that because the sweaters and mufflers are out, the umbrellas must be put away is not always correct. The rain clouds can always break through and reverse the prevailing  cold weather.