Monday, September 24, 2012

North Atlantic Oscillation (NAO) could be the wildcard this Indian Winter

Experts in climate change and the changing environment of the Himalayan region said Sunday's avalanche that left at least nine dead and five others missing in northern Nepal was caused by large quantity of soft snow that had piled up since Sept. 14.
"In the past three days, the mercury went on increasing in the Himalaya region and it was so hot in the region and it slowly started melting new snow which were accumulated in the region, resulting in an avalanche,"
said Dr. Arun Bhakta Shrestha, a climate change expert and member of the International Center for Integrated Mountain Development (ICIMOD) Nepal.”
Himachal Pradesh also experienced heavy snowfall around September 14th which have now melted away.

So what's happening? As seen in the North Atlantic Oscillation (NAO) Index, the NAO switched to its positive mode around September 14th which intensifies and increases frequencies of western disturbances (westerlies) that in turn increase precipitation, both rainfall and snow. Around September 17th, it switched back to its strongly positive mode and the result the avalanche due to the rapid melting of the snow.

Normally in an El Nino year we should experience a warmer than average winter. But the NAO could be the wild card this winter!

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