Second monsoon ‘break’ leaves large rain deficiency in August

In August, there is 33% deficiency in rainfall over the country with 51% deficiency over central India; 22% deficiency over northwest India; 37.7% deficiency over peninsular India and 5% deficiency over east and northeast India
Representational image. (Satish Bate/HT PHOTO)
Representational image. (Satish Bate/HT PHOTO)
Published on Aug 17, 2021 06:05 PM IST
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By Jayashree Nandi

Monsoon in the first half of August has been subdued over most parts of the country, according to India Meteorological Department’s data. In August, there is 33% deficiency in rainfall over the country with 51% deficiency over central India; 22% deficiency over northwest India; 37.7% deficiency over peninsular India and 5% deficiency over east and northeast India.

This has also brought down the cumulative rainfall received during the monsoon season so far with a 9% rainfall deficiency from June 1 to August 16 over the entire country. There is 8% deficiency over northwest India; 11% deficiency over east and northeast India; 13% shortage over central India and 5% excess over south peninsula.

This was mainly due to “break” monsoon conditions in the last couple of weeks when the monsoon trough was mostly over the Himalayan foothills. There was a “break” in monsoon rain in July also from June 29 to July 11. Monsoon may pick up gradually from Wednesday. “We had break monsoon conditions in August as the monsoon trough remained near the foothills most of the time leading to scanty rain over the plains. The Madden Julian Oscillation (MJO) was also at an unfavourable location leading to scanty rains. There was a long break phase in July also. But now there is a new monsoon pulse over southern peninsula which will move upwards gradually. A low-pressure area which has formed over northwest Bay of Bengal will also bring rain in its path,” said DS Pai, senior scientist at IMD Pune.

Also Read | Dry spell set to end, IMD predicts rain from August 20

In August, rainfall was limited to east Rajasthan and west Madhya Pradesh where flooding was reported due to excess rain. But there was a 56% deficiency over Haryana, Chandigarh and Delhi region; 50% deficiency over west Rajasthan; 63% over Punjab; and 90% deficiency over Gujarat region.

“The deficiency is mainly due to break monsoon conditions. But with the movement of the low pressure system we are expecting rains to commence over central India including Maharashtra, Madhya Pradesh etc and then over parts of northwest India from August 19. Easterly winds at lower levels have started picking up over some parts of northwest India,” added RK Jenamani, senior scientist, national weather forecasting centre, IMD.

On Tuesday, IMD said there is likely to be revival of monsoon activity over northwest India with enhanced rainfall activity over Madhya Pradesh, Maharashtra, Gujarat region and Chhattisgarh till August 19 and over northeast India and Sub-Himalayan West Bengal and Sikkim till August 18.

There is a low-pressure area over coastal Odisha and adjoining northwest Bay of Bengal. It is likely to move west-northwestwards during the next 48 hours across interior Odisha, Chhattisgarh and northeast Madhya Pradesh. The western end of monsoon trough is north of its normal position and the eastern end is south of its normal position and passes through the centre of low-pressure area over coastal Odisha and adjoining northwest Bay of Bengal to eastcentral Bay of Bengal. The western end of monsoon trough is very likely to shift gradually southwards towards its near normal position during the next two days. Strong southerly winds from Bay of Bengal to northeast India will continue to prevail till August 18.

There is a warning for increased rainfall activity over northwest India from August with widespread rainfall activity and isolated heavy rainfall likely over Uttar Pradesh, Uttarakhand and Himachal Pradesh from August 19 to 23; over Haryana, Chandigarh and Delhi on August 20 and 21; heavy to very heavy is also very likely over Uttarakhand on August 19 and 20. “Rains during the second half may help cover the rain deficiency during monsoon season,” added Pai.

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Sunday, October 17, 2021