First time in five years, arrival of northeast monsoon coincides with retreat of southwest monsoon1 min read . Updated: 18 Oct 2019, 05:42 PM IST
- Unlike the four-month southwest monsoon which provides over 75% of the annual rainfall to the country
- The southwest monsoon begins its withdrawal from West Rajasthan on September 1
NEW DELHI : It is for the first time in last five years, that north-east monsoon arrived on the same day when the four-month southwest monsoon completely withdrew from the country.
“The last, it happened was in 2014, when both the withdrawal of southwest monsoon and arrival of northeast monsoon took place simultaneously on October 18. A similar pattern was observed in 2013," said one of the senior scientists at IMD.
Normally, the southwest monsoon begins its withdrawal from West Rajasthan on September 1 and takes roughly about 45 days to completely retreat from the country. However, over the years, its retreat is beginning to delay until September-end. This year, the monsoon began to retreat on October 8, which was the longest delayed withdrawal ever.
A longer monsoon season is also shrinking the gap between the southwest monsoon and arrival of north-east monsoon, which usually makes its onset over the southern coast on October 18.
“2010 onwards, the shift is clearly visible. The monsoon season is getting longer, and withdrawal is getting pushed to a later date. It is mostly because, more low pressure systems are forming over Bay of Bengal which are keeping the monsoon active and bringing rains in September," said Dr K J Ramesh, former Chief of Indian Meteorological Department (IMD), New Delhi.
While the shift could be seen as a manifestation of climate change, scientists say, it is also leading to a sudden arrival of winter with lowering of temperatures.
“The current monsoon season was unique in several ways, especially the way it departed. Normally, if the withdrawal begins around September 1, it takes roughly about 45 days to completely retreat from the country, this year, it withdrew from the country within eight days," said S Hosalikar, Deputy Director General, Western Region, IMD.
Unlike the four-month southwest monsoon which provides over 75% of the annual rainfall to the country, the rainfall during the north-east monsoon season is limited to only the southern peninsula. It provides rainfall to Tamil Nadu, coastal Andhra Pradesh, Rayalseema, Kerala and south-interior Karnataka during October to December, which is crucial for the cultivation of Rabi crops like Wheat.