IMD predicts monsoon retreat in NW India around September 19
What's the story
The India Meteorological Department (IMD) has predicted that the monsoon will soon start retreating from North-West India. The process is expected to start in West Rajasthan around September 19, nearly two days late. However, a low-pressure area over southeast Rajasthan and adjoining north Gujarat is likely to keep the atmosphere moist and unstable, to cause heavy rainfall in the region.
Weather transition
Major shift in atmospheric conditions
The monsoon's retreat will lead to a major shift in the atmospheric conditions.
Moisture-laden easterly winds will be replaced by dry westerly and north-westerly winds from Pakistan, Afghanistan, Iran, and the Arabian Gulf.
The IMD looks for a sustained change in atmospheric patterns before declaring a withdrawal. This includes reduced rainfall over five consecutive days and clearer skies.
Weather patterns
Rainfall deficit across the country
The withdrawal line may not move southward in a straight, daily manner. It could stall for days before moving toward Central and Peninsular India.
India's cumulative rainfall deficit stood at 15% as of Sunday, with the South Peninsula witnessing the highest shortfall at 28%.
East and North-East India had a deficit of 25%, while North-West and Central India recorded deficits of 10% and 6%, respectively.
Weather systems
Monsoon trough continues to run through Rajasthan, Gujarat
The monsoon trough continues to run through southeast Rajasthan, north Gujarat, Rajgarh, Damoh, Pendra Road, Rourkela, and Digha before entering the north-west Bay of Bengal.
An upper-air cyclonic circulation is over the north-west Bay and adjoining coastal Odisha and West Bengal. Another circulation over Coastal Andhra Pradesh has merged with this system.
This keeps the Bay under watch for another possible 'low' formation.
Rainfall forecast
Warnings for fishermen due to bad weather
A secondary trough extends from the Rajasthan low across Madhya Pradesh and north Chhattisgarh.
A western disturbance runs roughly along Sriganganagar in Rajasthan and Bathinda in Punjab.
Another rain-bearing trough extends from South Interior Karnataka to the south-west Bay across Tamil Nadu.
These active weather systems are expected to keep several parts of India under heavy rainfall for some time.
Fishermen have been advised against venturing into both the Bay of Bengal and the Arabian Sea due to these conditions.