108% rainfall recorded as monsoon withdraws
The monsoon officially ended on Wednesday with the country recording rainfall that was 108.7% of the long period average (LPA) according to India Meteorological Department, although there were significant regional and temporal variations. For instance, August received the most rains in 44 years.
This is considered an ‘above normal’ monsoon. In June, IMD forecast ‘normal’ monsoon rain of 102% of LPA with error margin of +/-4% for the season.
Rainfall range of 96 to 104% of LPA is considered normal and 104% to 110% is considered above normal. Last year India recorded ‘above normal’ rain of 110% of LPA making 2019-20 consecutive years of above average monsoon.
This season (June 1 to September 30), northwest India recorded 84% of LPA; central India, 115%; the southern peninsula, 129%; and east and northeast India, 106%. Since a +/- 19% band is considered normal this means rains in northwest India were not deficient, ahtough those in the southern peninsula were excess.
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LPA is the average of monsoon rain recorded between 1961 and 2010. This year 95.8 cm rain was recorded against long period average of 88.0 cm for June, July, August and September.
Out of 36 meteorological subdivisions in India, two recorded large excess rain ( 60% over LPA ) -- Rayalseema (82%) and Saurashtra and Kutch (126%); 12 recorded excess rain (20% to 59% over LPA); and 17 subdivisions received normal monsoon rainfall (-19% to 19% of LPA) ; and only five subdivisions received deficient rainfall. These are Nagaland, Manipur, Mizoram and Tripura (- 32%), West Uttar Pradesh (-37%), Uttarakhand (-20%), Himachal Pradesh (-26%), and Jammu & Kashmir and Ladakh (-33%). IMD’s map shows extremely heavy rainfall spells of over 20 cm were concentrated along the west coast; central India and northeast India.
On Wednesday, the monsoon withdrew from most parts of Rajasthan, parts of Punjab, the entire western Himalayan region, Haryana, Chandigarh, Delhi and some parts of Uttar Pradesh. The withdrawal line is passing along Lakhimpur Kheri, Shahjhanpur, Alwar, Nagaur etc in northwest India according to IMD. Complete withdrawal of monsoon from the entire country is expected by October 15.
Cyclone Nisarga which formed over Arabian Sea helped with timely monsoon onset over Kerala on June 1; it pulled the monsoon winds inland along the west coast. The monsoon advanced well and covered the country by June 26 but July rains were inadequate. The weak monsoon in July was mainly due to absence of any major monsoon disturbance formation over Bay of Bengal. The monsoon trough lay to the north of the normal position near the Himalayan foothills leading to prolonged and intense flooding in the north-eastern states and Bihar. Central and northwest India remained deficient in July.
In August, there were back to back formations of low-pressure systems over the north Bay of Bengal and they moved mainly towards Gujarat and south Rajasthan. Five low pressure systems formed over Bay of Bengal which caused higher than normal rainfall over central and western parts of the country. The Arabian Sea was very active with stronger winds reaching up to 50-60kmph . There were two to three spells of riverine floods over Odisha, Telangana, Madhya Pradesh, south Gujarat and south Rajasthan according to IMD. August recorded 127% of LPA, the highest in 44 years and the fourth highest in the last 120 years, said RK Jenamani, senior scientist at National Weather Forecasting Centre.
The monsoon started withdrawing from the western parts of northwest India on September 28, delayed by 11 days compared to the normal date for commencement of monsoon withdrawal.
“We are analysing the monsoon data and will soon release a comparison with our long range forecast ,” said IMD chief Mrutyunjay Mohapatra.
The all India average of monsoon rainfall was normal as per definition. However, that doesn’t give much insight into the regional manifestation of the monsoon.
“Extreme rain destroyed crop in many places. In Andhra and Telangana there were two spells of extremely heavy rain which destroyed vegetables, groundnut and pulses in many places. The market price for pulses now is 30 to 40% higher than MSP which is a huge problem for farmers. Another issue is that both Telangana and Andhra farmers dont have insurance this time because the states plan to launch their own insurance company soon. So it’s a really worrying situation,” said G V Ramanjaneyulu, executive director, Centre for Sustainable Agriculture, Hyderabad