Sunday, November 07, 2010

From a reader.. "4 - 6 cm rain through out North and Coastal tamilnadu with a category 1 storm is worthless"


  1. Why do you say its worthless?

  2. Anonymous7:57 PM

    Because, if you look at the annual rainfall (Chennai Airport for say, it had only 98 cms till date, where as annual normal is 135 cms). We need 40 more cms before Dec and we are already into Nov Mid.
    Also, Major portion of rain this year came through SW monsoon. This means, with the deficit downpour that happens between Sep-Dec, the city will have to survive till June of next year.
    Also, looking at the amount of rainfall, you typically would get 4 cms of rain in one hr with a local thunder cell. So, with 12 hrs of rain amounting to 4 - 6 cms that too with a cyclone is worthless.
    Another point here is cyclone eats up lot of time to build up and supresses rainfall activity for few days before action and after action. This would be around 5 - 7 days of lull in total. Also, when the system tracks in a different direction, you wouldn't get a single drop of rain but have to wait for 10 days for the next system to get activated.

  3. That's a good enough explanation:). It's been however really good for semi-arid Pavagada district of Karnataka where the additional 40-50 mm means about 2500 litres of rooftop rainwater harvested.
    This will tide families over this years drinking and cooking water requirement in this Fluoride affected area.
    Always look at the bright side of life :):)

  4. Exactly - agreed. Predictions about 300mm -500mm rain proved to be wrong. Not sure how long will NEM sustain?
    Nowadays - this year even desert areas of Rajasthan got 500mm - 500mm during 2 continous days.