Read
http://www.flonnet.com/fl2217/stories/20050826005101200.htm.
Dr Ramachandran (affectionately called Bajji by friends) once again lends solid perspective on the Mumbai cloudburst in late July.
In the current issue of Frontline (Volume 22 - Issue 17, Aug 13 - 26, 2005), he gives a lucid explaination of why the intensity of the rain that lashed Mumbai could not have been predicted accurately.
Taking a decision based on probability is common, but implicit, in business as well as science. The historical chance of such a cloudburst over Mumbai was just 0.01. The 'preparedness' of civil systems, and even use of weather forecasting terminology, reflect that. The civil machinery in Chirapunji would not (should not) have been surprised by this.
But there are problems. Ramachandran points to the India Meteorological Department (not Indian, a common mistake), that has been functioning like a chicken without a head for many months now. He also cites lack of anticipation on part of weathermen, given conditions prevailing over the western ghats at that time.
Now, add to this the perennial apathy of civil machinery in Mumbai.
Suppose, it was Hyderabad...One wonders how Hyderabad would have coped with such a cloudburst. August 2000 was the closest we came to such a situtation. Following heavy overnight rains, all lakes in Hyderbad were overflowing, including the 'gentle' Hussain Sagar. We were at Bowenpally at that time. The Hasmathpet Lake in the undulating Bowenpally region (Secunderabad) burst its banks and flooded colonies that were downhill. Our house was flooded too. Thankfully, it was on a raised foundation, and we could wade out in thigh deep water. Other creatures were happy about our house -- frogs, squirrels, lizards had found an island. A lot of cleaning up that week.
Guess Hyderabad's natural drainage maybe better off since it is on the Deccan Plateau. The rocky terrain may offer run-off channels into dry, water-deficient regions surrounding the city. North Mumbai was unfortunate to be caught between the hills to the northeast and the sea, in high tide, to the west. Add to this unauthorized and unplanned concrete jungles that dot the Mumbai beach-heads, blocking all natural streams.
[p.s: For those really keen on how satellite weather photography, there a couple of pictures from the Tropical Rainfall Measuring Mission (TRMM) satellite.]