Officially, the monsoon season has come to an end, with above normal rainfall
Conditions favourable for withdrawal from north-western parts within next 24 hours
New Delhi: The southwest monsoon is all set to start retreating from 10 October, the India Meteorological Department (IMD) said on Tuesday, after knocking the record for the longest-delayed withdrawal, and illustrated with several extreme rainfall events that caused large-scale loss of life and property.
The current forecast indicates conditions are becoming favourable for withdrawal of the monsoon from major parts of North-West India within the next 24 hours, after which IMD could declare its withdrawal.
There is persistence of an anti-cyclonic circulation over North-West India, which is most crucial for withdrawal of the monsoon along with gradual reduction in moisture and reduction in rainfall. An anti-cyclonic circulation is basically a certain type of wind flow in a high pressure system which is associated with cloudless skies.
For the first time in the past 58 years, monsoon’s withdrawal has been delayed to 10 October. The last time it got delayed the most (1 October) was in 1961.
The monsoon, which brings more than 75% of India’s annual rainfall during its four-month journey normally begins to withdraw from west Rajasthan around 1 September. However, over the last few years, its withdrawal has been facing delays of several weeks.
According to the weather department, the delay was caused due to the persistence of rains over the western parts of the country till September-end.
Not only there was a low pressure system over Rajasthan on 1 October, a fresh western disturbance also affected the western Himalayan region and brought scattered rainfall over Jammu and Kashmir and Himachal Pradesh earlier this week. The current season also saw the second-wettest September after 1917 with rainfall at 152 % of the long-period average (LPA) of 88cm.
It was also the first time after 2010 when rainfall during the last three months of July, August and September even exceeded the LPA of 88cm. This, despite the fact, that the monsoon’s arrival was delayed by a week and June ended with a staggering rainfall deficit of 33%.
Officially, the monsoon season came to an end on 30 September with above normal rainfall which was 110% of its LPA of 88cm.
In a major improvement from last year, the country received excess rains to the tune of 10%, with total 12 out of 36 subdivisions recording excess rains and normal rainfall in other 19 subdivisions. This helped improve the drought conditions, especially in Maharashtra, Jharkhand, Tamil Nadu and Andhra Pradesh.
However, the situation was not very good for Haryana, Chandigarh and Delhi which recorded the maximum rain deficiency of 42%.
The overall rainfall was much better than what was predicted by IMD, according to which the season was likely to end with normal rains at around 96% of LPA with a model error of +/-4%.
M. Mohapatra, director general of meteorology (DGM), IMD says it was mainly due to the low pressure systems, associated with rains which persisted for longer number of days.
“There were three main reasons: first, the weak El Niño conditions turned to neutral during the second half of the season which favoured the monsoon current, then the Indian Ocean Dipole (IOD) moment also turned positive in September and third, the number of low pressure systems which formed over north Bay of Bengal not only persisted for longer duration but also travelled up to Gujarat and Rajasthan. This way, we got very good rains over central and peninsular India," said Mohapatra.
East Rajasthan received surplus rains to the tune of 53% compared to just 3% last year, and west Madhya Pradesh, received excess rains to the tune of 61% compared to a deficit of 4% last year.