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Expect normal rainfall in July, says IMD amid 10% deficiency
There is likely to be normal monsoon rainfall in July with the number veering towards the positive side of the normal range, the IMD said.
New Delhi: There is likely to be normal monsoon rainfall in July (between 94 to 106% of the long period average or LPA) , with the number veering towards the positive side of the normal range, the India Meteorological Department said on Friday.
June ended with a rain deficiency of 10% on Friday, but, in keeping with a familiar recent trend, with wide variations across regions -- a 42% excess over northwest India; a 18% deficiency over east and northeast India; a 45% deficiency over the southern peninsula; and a 6% deficiency over central India . IMD however said the rain deficiency may be covered to large extent in July which accounts for almost exactly a third of the overall rainfall in the season.
Monsoon rainfall is expected to be normal over the country at 96% of LPA, with an error margin of +/-5%, IMD had forecast in April and again in their May update. The LPA for monsoon is calculated based on rainfall data during 1971 to 2020 which is 87 cm.
According to official data released on Friday, uneven monsoon has impacted the planting of rice, the main summer staple, with farmers planting the grain in 2.6 million hectares as on June 30, nearly 26% less compared to the corresponding period last year.
The LPA of rainfall over the country during July is 280.4 mm based on the data of 1971 to 2020. There is likely to be normal to above normal rainfall over most areas of central India and adjoining south peninsular and east India and some areas of northeast and northwest India in July, IMD said, but below normal rainfall over many areas of northwest, northeast and southeast peninsular India.
“A low pressure area is expected to develop over Bay of Bengal around July 4 which may bring good rainfall over central and northwest India. We are also expecting monsoon rainfall to pick up over the west coast. An offshore trough is expected to develop over Arabian Sea which is expected to bring on active monsoon conditions over the west coast. At the moment we can only speculate that these factors will help monsoon conditions in July which is also reflected in our models,” said M Mohapatra, director general, IMD.
Currently, warm El Nino Southern Oscillation neutral conditions are prevailing over the equatorial Pacific. The sea surface temperatures (SSTs) across most of the equatorial Pacific Ocean are warmer than normal and near El Nino threshold value, according to IMD. The latest forecasts by global models indicate high probability for the El Niño conditions to develop during the middle of the monsoon season and continue till the first quarter of 2024. Presently, neutral Indian Ocean Dipole (IOD) conditions are prevailing over Indian Ocean. Positive IOD conditions are likely to develop during the remaining period of the monsoon season, IMD added.
El Nino has a strong influence on the southwest monsoon in India. El Nino is characterised by an unusual warming of waters in the eastern equatorial Pacific, which has a high correlation with warmer summers and weaker monsoon rains in India. Positive IOD on the other hand is good for southwest monsoon over India. IOD refers to the temperature differential between the western and eastern Indian Oceans. A positive IOD has a direct correlation with a good monsoon.
Patchy rainfall and extreme heat stress over east India
Following a week’s delay in monsoon onset over Kerala, there was very slow progress of monsoon with rainfall picking up only during the last week of June especially over northwest, central and parts of east India. “Though cyclone Biparjoy which formed on June 7 helped with monsoon onset and its progress over the west coast, once it moved northwards and got detached from the monsoon flow, monsoon progress weakened over the country. The formation of a low-pressure area over Bay of Bengal last week helped activate both the Arabian Sea and Bay of Bengal branches of monsoon and bring widespread rainfall over northwest and central India,” said Mohapatra. Out of 36 subdivisions, 17 subdivisions continue to record deficient rain (-59% to -20%); 8 recorded normal rain (-19% to 19%); 6 recorded excess rain (20% to 59%); 3 large excess (60% or more); and 3 large deficient (-99% to -60%). Kerala is the worst hit -- with a large deficiency of 60%. Bihar also has deficiency of 48%. There were also 62 extremely heavy rainfall events in June (over 20.45 cm).
IMD’s extended range forecast indicates widespread rainfall over Himalayan foothills including Bihar until July 6. Thereafter there is an overall reduction in rainfall activity which is expected to pick up over the west coast and central India during the week of July 21 to 27.
“After monsoon onset the west coast, the west coast received rainfall but not the interior parts of peninsular India especially Karnataka, Maharashtra, Telangana, Andhra Pradesh, Odisha. Monsoon reached east India very late and there is still a lot of deficiency over Bihar and Jharkhand. The Nagaland, Mizoram, Manipur and Tripura region continues to be deficient. Though northwest India has got good rainfall, it is gradually expected to reduce from July 2. The picture for July will become clearer in a few days. Though June is important for sowing, agriculture wise July and August are most critical,” said Mahesh Palawat, Vice President, Climate and Meteorology at Skymet Weather.
“It rained only a few pockets in June. It was not well organised. I guess it will further slowdown at least for next one week. Rainfall deficiency could increase,” said M Rajeevan, former secretary, ministry of earth sciences.
“We see a clear shift in monsoon patterns, now with long dry periods interspersed with heavy rains rather than moderate rains spread throughout the season. That’s a climate change signal, though we had multiple factors playing the monsoon chase this time. To start with, the monsoon was weak and delayed, usually the case with an early El Nino. Weak monsoon winds and warm Arabian Sea sowed the seeds for cyclone Biparjoy. Biparjoy took most of the moisture away from the monsoon, so we got less rain during the first three weeks of June. Also, the cyclone resulted in enhanced convection over the sea but a compensating dry air sinking over India. This, along with the rainfall deficiency raised the heat over central and north India,” said Roxy Mathew Koll, climate scientist at Indian Institute of Tropical Meteorology said on earlier in the week.
According to India’s agriculture ministry, 51% of India’s farmed area, accounting for 40% of production, is rain-fed, making the monsoon critical. With 47% of the country’s population dependant on agriculture for their livelihood (according to this year’s Economic Survey), a bountiful monsoon has a direct correlation with a healthy rural economy.
