Is monsoon currrent from Bay of Bengal weakening over plains of north India?

Data from India Meteorological Department too partially support this view

Is the monsoon current emanating from Bay of Bengal shifting its position more towards central part of India causing more rains over Madhya Pradesh, Chhattisgarh, Odisha, Telangana, leaving less for Punjab, Haryana and Delhi?.

Well, a section of meteorologists definitely believe so. Data from India Meteorological Department (IMD), too partially support this view.  

The data show that total rainfall received in plains of North-West India, comprising Punjab, Haryana, Delhi and Rajasthan, has fallen from 686.8 millimeters in 2010 to 654.8 milimeters in 2011 and 569 millimeters in 2012.  Barring 2012, rains were normal, which is 615 milimteres, in the region. 

However, the fall has definitely raised some doubts among minds of a section of meteorologists. North-west India gets its rainfall both from monsoon currents emanating from Arabian Sea as well as Bay of Bengal.

“Yes, the amount of rainfall that North-West India is getting since the last 2-3 years is falling, but it is well within the normal range and absolutely no cause for worry,” said D S Pai, director of Long Range Forecast in IMD.

Mahesh Palawat, chief Meteorologists at Skymet Weather Services Ltd, a private weather forecaster, said that monsoon current emanating from Bay of Bengal is showing definite signs of moving more towards the west or west -north-westerly direction, causing more rainfall over Telangana, North Andhra Pradesh, Madhya Pradesh, Chhattisgarh, rather than Punjab and Haryana.

He said this shift which can be because of climate change or something else is gradually pulling down the total rainfall over some parts of North western India.

However, Pai said it is not yet proved that rains from Bay of Bengal are shifting more towards central India.

In 2013, too, IMD in its second stage forecast has said rainfall during the four-month southwest monsoon season over much of North-West India is likely to below normal at 94% of the long period average.   

Till July 2, rainfall over much of northern India has been above normal. However, after the deluge seen in middle of June, rainfall over much of Punjab, Haryana, Rajasthan, Delhi and parts of Uttar Pradesh has taken a break, but it has revived strongly over central and western parts of the country.

“A trend of 2-3 years is too early to make any concrete judgment,” said former director general of IMD, Dr Ajit Tyagi. He said seasonal variation in rainfall needs to be followed for at least a decade to establish any firm trend.

As of now there is no cause for worry, he said. Plains of North-West India which comprise Punjab, Haryana, some regions of Uttar Pradesh and Rajasthan contribute over 80% of wheat and more than 60-70% of rice produced in the country.

But, the most heartening factor is almost 80% of total arable land in states like Punjab and Haryana is under irrigation.