Extended monsoon likely this year: IMD
Rainfall is likely to be deficient at least until September 13 in most parts of the country, including northwest and central India, before intensifying after September 17, according to the IMD’s extended range forecast.Updated: Sep 08, 2020, 00:57 IST
Monsoon rains are likely to enjoy another extended run this year in keeping with the trend over the past decade, the India Meteorological Department (IMD) said on Monday, emphasising that rainfall in September is likely to range between normal and above normal as the four-month weather phenomenon prepares for a late withdrawal.
Rainfall is likely to be deficient at least until September 13 in most parts of the country, including northwest and central India, before intensifying after September 17, according to the IMD’s extended range forecast. Normally, withdrawal of the monsoon begins on September 17 when the rains start reducing across the country until a complete withdrawal on October 15.
But this year, the IMD’s extended range forecast shows extensive and heavy rains along the west coast between September 11 and 24 and then until October 1 over several parts of central India, with complete withdrawal likely after October 15. An extended withdrawal process of the monsoon has become the norm over the past 10 years, officials say.
“We have indicated in our weekly weather update last week that withdrawal of monsoon may begin from western parts of Rajasthan in the week ending September 18. But we are also expecting a low-pressure area to develop over west-central Bay of Bengal around that time,” IMD director general M Mohapatra said at a press conference.
“So, while withdrawal of the monsoon may begin, we are still studying as to when it’s likely to withdraw completely. Withdrawal is likely to be extended. We are expecting normal to above normal rain in Kerala, Karnataka and coastal areas of Maharashtra around and after September 17,” he added.
According to the new monsoon onset and withdrawal dates released by the IMD in April factoring in the trend of delayed monsoon withdrawal, the normal date for the monsoon to begin withdrawing is September 17; it withdraws completely by October 15. The dates were September 1 and October 15, respectively, until last year. The new onset date is based on an analysis of monsoon data from 1961 to 2019 and withdrawal date on data from 1971 to 2019 by scientists at the IMD, Pune.
Last year the monsoon started withdrawing on October 9, against the normal date of September 1, and prolonged rains brought a deluge in parts of Maharashtra, Kerala and Bihar in August when rainfall usually reduces. The monsoon completed its withdrawal by October 17.
“It’s very difficult for us to say immediately when will it stop raining completely and withdrawal can be announced. We are seeing a pattern of delayed monsoon withdrawal in recent years which needs to be investigated carefully,” Mohapatra said, adding that intra-seasonal variability of the monsoon has been high this year with rainfall excessive in June and deficient in July. August recorded excess rain by a high margin.
An active Madden-Julian Oscillation -- characterised by an eastward shift of clouds and rainfall near the equator that recurs every 30 to 60 days -- and cold El Nino neutral conditions favoured good rains in August, he said. “Rain in September is likely to be normal or above normal,” Mohapatra added.
A cool El Nino neutral phase indicates that the sea surface temperature is cooler than normal in the tropical Pacific Ocean. It is usually linked to above-normal monsoon rains over India.
“This year a good monsoon should have helped farmers and the output must be very good. We don’t have an assessment as to how it will impact the economy,” said M Rajeevan, secretary, ministry of earth sciences.
Monsoon rains are critical because nearly 60% of India’s net arable land lacks irrigation and half the population depends on agriculture for a livelihood. With good rains, spending by rural consumers on manufactured items such as television sets and gold jewellery goes up, and boosts factory output. A deficient monsoon cuts rural consumption and also drives up inflation.
There was 17% excess rain in June with heavy rain and flooding in Saurashtra and some north-eastern states; July rainfall was 10% deficient, but the month was marked by heavy to extremely heavy rain in north-eastern states which led to floods in Bihar, Assam, some pockets of eastern Uttar Pradesh, and Arunachal Pradesh, and landslides in Assam, sub-Himalayan West Bengal and Sikkim.
Rainfall was 27% excess in August, mainly due to extra rain over Rajasthan, Gujarat, Maharashtra, Karnataka, Kerala, Telangana, Chhattisgarh and Odisha because of five low-pressure areas developing over the Bay of Bengal. This led to frequent floods and inundation of low-lying areas and urban flooding over different areas; landslides occurred in the Ghat sections of Karnataka and Kerala, Mohapatra said.