South Asian Monsoon and Impacts in Karakoram. The effects of the Indian Ocean and Bay of Bengal Monsoonal flows have direct effects upon the lives and inhabitants in much of Asia and critical for the agriculture of the region. The monsoon moisture greatly impacts climbers and trekkers in the Himalaya and north and west into to the Karakoram climbing region as well.
The map above indicates that the heating of Nepal Plateau brings an area of low pressure over Tibet Plateau Air. The main impact is air flows from an area of “relative” higher pressure (Bay of Bengal) to an area of “relative” lower pressure (Tibet Plateau). Thus, as the monsoon moisture moves northwards it brings rain, sometimes huge amounts, into the lower plains of the Indian Basin. Bangladesh, lying mostly at sea level suffers immense floods most every year because of this. This can be the case in June. As the moist air rises against the Himalayas it cools bringing rain and considerable snow to the mountains. This gives hikers and climbers a narrow window for executing their plans which is before the monsoon setting up which is usually by June 1. They return in September and beyond as the monsoon retreats.
As the summer advances the monsoon moves to the north and by the middle of July reaches it’s furthest point north, Pakistan. Thus, when the monsoon reaches it’s furthest point north is when climbing areas in the Karakoram are the most impacted with clouds and precipitation. The retreat back towards the south can be a slow process which climbers await.
Also during the monsoon cyclones can form in the Bay of Bengal and can bring heavy precipitation to the area as moves well to the north. Cyclones are also common in the fall as well
Article written by Robert Morthhorst and edited by Meteorologist Michael Fagin