The years when India records a good monsoon are generally marked with numerous rainy spells in different parts of the country at this time of year. But this time, the situation is different as the monsoon has weakened due to several local conditions that are halting its northward journey.
Experts say the weakening of monsoon started from June 21 and it is likely to weaken further from June 29 until July 5 when it is expected to strengthen again.
This year, the monsoon started with good rains in most parts of the country like the peninsular region, the western coast, the central region and even in the North East.
Until some weeks ago, monsoon’s advancement was so strong that at one point the India Meteorological Department (IMD) predicted it would reach Delhi by June 15.
However, due to several inter-seasonal developments, its northward advancement has slowed down.
Since June 21, monsoon has remained active in central and eastern parts of the country while the southern peninsular region too has received some rain.
As per IMD’s forecast, Bihar, eastern Uttar Pradesh and parts of Karnataka are likely to continue receiving rain until Monday. However, after that, monsoon is likely to weaken for at least a week.
Senior IMD scientist RK Jenamani explains, “Normally when the Southwest Monsoon starts from the Arabian Sea, the monsoon system travels in the form of waves, reaching different parts of the country. It is helped by low-pressure system in the Bay of Bengal, which pushes it further in the Northwest direction. This time, there were easterly winds but they were not strong enough to reach the Northwestern parts of the country. Hence, it provided rain till eastern Uttar Pradesh and some parts of western Uttar Pradesh too.”
Jenamani added that apart from this, generally during summers, there are no or very few Western Disturbances, which helps monsoon to move forward.
These systems are the backbone of monsoon development. From June 29, all these systems are becoming unfavourable, and hence monsoon rains are unlikely in most parts except the Eastern and Northeastern regions,” Jenamani said.
In addition to this, the global phenomenon of Median Julian Oscillation (MJO) is also impacting the progress of monsoon this year.
After moving to the Western Hemisphere, MJO normally takes a month to return to the Indian Ocean. When it moves away from the Indian Ocean, monsoon developments remain poor.
This year, MJO is moving slowly and has reached Eastern Africa so far. It will take some time to reach the Indian Ocean. This is another factor why the monsoon will remain weak for a while.
What is also unfavourable for monsoon’s advancement this time is that there are too many Western Disturbances this year. Unlike the Western Disturbances that occur during winter, the ones in summer are dry. They thus push the easterlies and affect monsoon advancement adversely.