Second Rainest Monsoon in 26 Years
Delayed Withdrawal Commences After Second Rainiest Monsoon in 26 Years; Below-Normal Rain Forecast for Next Three Months...!!!
Amid all the gloomy news around the world and the economic slowdown, one positive for India has been the above-normal rainfall this monsoon season. Monsoons govern the economy in India as a large component of the Indian population depends on rainfed agriculture. The official monsoon season is about to end, and India has logged 954.3 mm rainfall so far as against the seasonal norm of 880 mm—9% above normal.
As per the India Meteorological Department (IMD) records, this is the second rainiest monsoon in the last 25 years, after 968 mm in 2019. It was only in 1994 that India recorded more average monsoon rainfall (1001 mm) than these two years.
Extended monsoon season
On Monday, September 28, the withdrawal of monsoon commenced over parts of northwest India, as confirmed by the IMD. Monsoon, however, has remained active over southern and northeastern parts of India with isolated heavy rains over Assam, Meghalaya, Tamil Nadu, Andhra Pradesh, Kerala and Karnataka. Parts of Tamil Nadu like Cuddalore and Nagapattinam were lashed with more than 120 mm rainfall over the past 24 hours till Tuesday morning.
An anticyclonic circulation is now established over the western parts of Rajasthan and Punjab leading to substantial reduction in moisture content and rainfall. The withdrawal of monsoon is declared when three conditions are met—no rainfall for continuous 5 days, establishment of anticyclone, and considerable reduction in moisture content.
This year, the monsoon poured bountiful water over the southern peninsula and central India. While southern states registered a whopping 29% excess rainfall this season since June 1, the central region recorded 15% more rainfall. Northwest India, on the other hand, witnessed a deficit of 16%. Coastal Karnataka was the wettest sub-division in India this monsoon, with an overall rainfall of a whopping 3,678 mm, while west Rajasthan was the driest with 331 mm.
The start of monsoon withdrawal has been delayed by 11 days compared to the normal date of September 17. Over the past four years, the withdrawal of monsoon has delayed repeatedly with withdrawal commencing only after September 27. Last year, the withdrawal started with a record delay of over 20 days on October 9. In 2019. IMD had revised the normal date of the start of withdrawal from September 1 to September 17.
Conditions have now become favourable for further withdrawal from parts of Haryana, Delhi and Uttar Pradesh in the next two days. In a normal year, the monsoon withdrawal happens up until Gujarat and Madhya Pradesh by the end of September. At the current rate, the withdrawal is likely to occur over Mumbai, Nagpur and Hyderabad by the second week of October.
Below normal rainfall in post-monsoon season
Clear blue sky over Delhi.
(Piyal Bhattacharjee/BCCL New Delhi)
After a wetter-than-normal monsoon season, below-normal rainfall is forecast over the next three months from October to December across the South Asian region, including India. The forecast has been issued by the South Asian Climate Outlook Forum and Climate Services User Forum in a consensus statement released on Monday. The forum was held online this year due to the ongoing COVID-19 pandemic.
As per the forecast, temperatures are also likely to remain in the normal to slightly warmer range across South Asia over the post-monsoon season. Weak La Niña conditions over Pacific Ocean and neutral Indian Ocean Dipole (IOD) conditions over Indian Ocean are likely to prevail throughout the upcoming season.
As the sun moves southwards post the September solstice, the Inter-Tropical Convergence Zone (ITCZ) also moves southwards, changing the trade wind regime from south westerly to north easterly. These winds usher in the onset of northeast or retreating monsoon over southern states of India, Sri Lanka and Maldives in October.
The forecasts suggest that below-normal rainfall is likely over southern Tamil Nadu this season, while central and eastern regions, including north Karnataka, Goa, Konkan, Madhya Maharashtra, Telangana, coastal Andhra Pradesh and Odisha, could witness above-normal rainfall.#Monsoon
Courtesy- India Monsoon Fb Page