New Delhi, The August 2010 flash flood in Leh that killed 193 persons along with severe damage that rendered hundreds missing and thousands homeless was caused by heavy rains for three consecutive days. The unusual rainfall is attributed to an easterly wind that transported clouds formed high over the Tibetan Plateau to Leh. These clouds also gathered moisture from the Arabian Sea, fed by the southwesterly winds and from the Bay of Bengal through southeasterly winds.
Usually, such a large storm system does not develop as cloud formation ceases during the night. But in this case, cloud formation was fueled by incoming moisture laden winds from three directions (easterly, southeasterly and southwesterly) throughout the night. Average total rainfall over Leh in August is about half-inch. But more than 8 inches of rain was recorded during this 24 hour period.
This event is reminiscent of flooding in the Big Thompson Canyon in Colorado in 1976 and the Black Hills of South Dakota in 1972. In all these cases, large organized clouds gathered high in the mountains and drew moisture up the slope of the mountain into the storms. The resulting heavy rains are uncommon in mountains, where there typically isn't enough moisture to cause such drastic rain. They are also more dangerous than storms in the plains.
