The Bay of Bengal branch is the most active one in the monsoon season. This branch strikes the coast of Myanmar and part of Bangladesh.
The Arakan Hills, however, deflect a big portion of this branch towards India. The monsoon, therefore, enters West Bengal and Bangladesh from south and southeast instead of from the south-westerly direction.
From here, this branch splits into two under the influence of the Himalayas and the thermal low is northwest India.
Its one branch moves westward along the Ganga plains reaching as far as the Punjab plains. The other branch moves up the Brahmaputra valley in the north and the northeast, causing widespread rains.
Its subbranch strikes the Garo and Khasi hills of Meghalaya. Mawsynram, located on the crest of Khasi hills, receives the highest average annual rainfall in the world.
Here it is important to know why the Tamil Nadu coast remains dry during this season. There are two factors responsible for it:
- The Tamil Nadu coast is situated parallel to the Bay of Bengal branch of southwest monsoon.
- It lies in the rain shadow area of the Arabian Sea branch of the south-west monsoon.
