HT Explainer: The monsoon is on a break. What does it mean? | Latest News India - Hindustan Times
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HT Explainer: The monsoon is on a break. What does it mean?

Jul 01, 2021 12:57 PM IST

The slowing down of monsoon could lead to a dip in agriculture production at a time when economic indicators are weak and the pandemic is yet to be controlled. This will clearly have livelihood implications

The Indian monsoon is taking a break even before it has covered the entire country. With the India Meteorological Department (IMD) saying it doesn’t know when the monsoon will revive, both farmers and policymakers are apprehensive. The slowing down of monsoon could lead to a dip in agriculture production at a time when economic indicators are weak and the pandemic is yet to be controlled. This will clearly have livelihood implications.

New Delhi, India - June 20, 2021: A cloudy sky and a view of the Qutub Minar, at Mehrauli in New Delhi, India, on Sunday, June 20, 2021. (Photo by Amal KS/ Hindustan Times) (Amal KS/HT PHOTO) PREMIUM
New Delhi, India - June 20, 2021: A cloudy sky and a view of the Qutub Minar, at Mehrauli in New Delhi, India, on Sunday, June 20, 2021. (Photo by Amal KS/ Hindustan Times) (Amal KS/HT PHOTO)

Here’s an explainer on this unusual monsoon break and its ramifications:

What is the nature of the Indian monsoon?

The Indian monsoon primarily affects India and its surrounding countries. It blows from the northeast during cooler months, and reverses direction to blow from the southwest during the warmest months of the year. So, in essence, strong easterly winds push the dominant westerly winds upwards, thereby taking over the dominant weather system for close to four months. The strong moisture laden winds being Bay of Bengal and Arabian Sea bring large amounts of rainfall to the region between June and September. The monsoon brings 50 to 70% of the total annual rainfall to the Indian sub-continent.

What are its common rainfall patterns?

Monsoon rains are not constant during the period. There are two rainfall-related phenomenon associated with monsoon — monsoon burst and monsoon break. In monsoon burst, heavy rainfall takes place over a long period, may be up to a week, in a region or regions of the country, primarily causing floods. Flooding in Kerala in 2018, or in Bihar and Assam in 2020 can be termed as instances of monsoon burst. The increase in intensity of both break and burst has been attributed to warming of earth surface because of the climate crisis.

What is monsoon break?

Monsoon break is a period when it goes into recession of one or more weeks. When tropical disturbances advance along the monsoon trough, at times, the sea level low pressure area weakens. As the high-level low pressure area moves north, precipitation decreases in the northern plains and it creates high pressure area over North Bay of Bengal, a rich source of monsoon rains.

This makes the monsoon trough along the west coast to weaken and monsoon winds from Bay of Bengal branch alone feed the monsoon trough, which runs along the foothill of Himalayas and Northeast India.

This, in turn, results in less or no rainfall across west coast, Deccan plateau and Northern plains. But a low pressure trough forms over the Tamil Nadu coast increasing the rainfall. As the monsoon trough runs close to the foothills of Himalayas, monsoon winds ascend the slopes of Himalayas resulting in orthographic rainfall. This is how a normal monsoon break works.

Why has monsoon receded now?

This monsoon break is slightly different. According to Mahesh Palawat of Skymet Weather, the monsoon break normally takes places once the entire country has had a spell of rainfall and monsoon coverage is complete. The break is mostly noticed at the end of July or in August. Monsoon again picks when it starts receding from September.

However, this monsoon break is unusual as it happening since monsoon has not covered all of India yet. Since June 18, very strong westerly winds are blocking the easterly monsoon wind, which brings moisture from Bay of Bengal and Arabian Sea. On the surface level, high velocity winds are blowing, causing ground temperature to rise and creating unfavourable conditions for monsoon winds to proceed.

The westerlies are strong because of the heating of equator near India and are blocking the easterlies, thereby pushing the monsoon down after it crossed Madhya Pradesh and covered half of Uttar Pradesh. So, only some parts of Konkan and Goa, the southern tip and northeast India is receiving good rainfall.

Is monsoon break common?

Yes, the monsoon break is common but not before the weather phenomenon covers entire country. Palawat said that it is rare for monsoon to experience a break before it covers the entire country.

“The break was because of very localised factors and failure of formation of westerly disturbance which could have pushed the monsoon upwards,” he said. The monsoon work on push and pull method, in which the low pressure in Bay of Bengal or Arabian Sea pushes the monsoon into Central India and weak westerly pulls the monsoon towards the western coast and northern India. This time, there was a push till June 18 when a low pressure had formed in Bay of Bengal but there was no pull. Emergence of strong and hot westerly winds has pushed the monsoon down.

When will the break end?

According to IMD, it is highly unlikely that the monsoon will resume till July 7. Palawat said there was no indication for monsoon trough to resume till July 8-10. “It is wait and watch till then,” he said.

Former director general of IMD KJ Ramesh, however, expressed confidence that there would be a vigorous monsoon by the second week of July and would cover the rain deficiency of the past 12 days. Till June 30, India received 13% more rainfall than normal but the showers are reducing since June 19, IMD rainfall data showed. The deficiency for last 11 days of June was 32% and for last day of June, it was 70%.

How is the heat wave related to monsoon break?

Dry and strong westerly winds from Pakistan and West Asia have brought heat wave across northern and central India, though late. Temperatures in several places in central and western India crossed 45 degrees Celsius on Wednesday. In normal weather conditions, this region sees heat wave conditions in late April, May or early June. Ramesh said this year, due to winds not been able to bring moisture from the seas, there is extreme dry weather creating heat wave-like conditions.

Is there any possibility of below normal monsoon?

Weather experts said it is too early to say. June is set to receive 106% of the Long Period Average (LPA) even though Monday and Tuesday saw 60% rain deficiency. The July prediction is 91% of LPA.

Skymet’s Palawat said there will be rain deficiency in the first 8-10 days of July and after that, the monsoon is expected to re-start and the gap can be covered. IMD said it doesn’t have a model to make precise prediction of monsoon rainfall for more than a week. So, they don’t know whether monsoon will revive after July 8, the day the monsoon is expected to cover entire India, almost 38 days after it hit the coast of Kerala. However, several places in western India, especially northern Gujarat and western Rajasthan, are witnessing drought-like conditions with negligible monsoon rainfall till now.

What could be the possible impact of this monsoon break?

Till now, experts say, there is not much impact of the break as there was good rainfall in May and first 17 days of June. Till June 30, India received 13% more rainfall than normal but the showers, as noted above, are reducing since June 19.

However, a long monsoon recession (beyond July 10) can delay sowing of crops, especially in the rain-fed areas, which is 40% of country’s agriculture land. It will also impact horticulture crops in Uttarakhand, Himachal and Jammu and Kashmir, especially apples. If it doesn’t rain in the next fortnight, the quality of the produce can be impacted.

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  • ABOUT THE AUTHOR
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    Chetan Chauhan is National Affairs Editor. A journalist for over two decades, he has written extensively on social sector and politics with special focus on environment and political economy.

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