IMD officials pointed out how October remained one the most erratic months ever, when the country witnessed as high as 36 extremely heavy (more than 204mm rain in 24 hours) events against a normal of 10 or 12 events in the month in recent years.(Representational Photo) The India Meteorological Department (IMD) has warned of more rainy days during November over south India, especially Kerala, in what seems to be a continuing and lasting trend since September.
October this year was the wettest-ever month for Kerala, when 589.9 mm of rain was recorded against a normal of 330 mm, since 1901. Similarly, Uttarakhand recorded its fifth wettest October this year.
Dr Mrutyunjay Mohapatra, director general of the India Meteorological Department (IMD), on Tuesday said that southern peninsular India is most likely to receive 122 per cent rainfall with respect to its long period average (117.5mm) this month.
After onset over south India on October 25, the northeast monsoon has been active and causing continuous rainfall. This monsoon mostly affects Kerala, Mahe, Tamil Nadu, coastal and interior Karnataka, Andhra Pradesh and Telangana.
“As per the latest Extended Range Forecasts, rainfall will continue over south India, particularly Kerala, till November 11,” said Mohapatra while releasing the November rainfall forecast of the country.
Last month, the IMD confirmed the evolution and development of La Nina conditions, a phenomenon when the equatorial Pacific Ocean remains cooler than normal. It is one of the main influencing factors on monsoons and regulates temperatures around the world. Normally, during La Nina years, the northeast monsoon is below normal. A number of weather models suggest that this cycle of La Nina will prevail all through the winter season and could last till May 2022.
“However, given the surplus rainfall recorded already during October and with more rainfall forecast during November, this theory will not hold true for the 2021 La Nina event,” explained Mohapatra, who assured that not much rainfall is expected during November over north, northwest and central India.
This is particularly important when places including Delhi, Uttarakhand and Uttar Pradesh reported some very heavy rain in October. The highest-ever 24-hour rainfall was recorded over Champawat (580mm) and Nainital (530mm) in Uttarakhand last month, triggering landslides and floods.
But surplus rain during a La Nina year is not rare either, said Mohapatra. IMD records show a similar higher rainfall trend during the northeast monsoon season in 2010.
On south India’s wet November, the IMD chief said the simultaneous active phase of multiple favourable weather systems will keep the northeast monsoon active this month. “The prevalence of strong easterly winds and the favourable positioning of the Madden Julian Oscillation will positively affect rainfall activity over southern peninsular India in November,” he said.
IMD officials pointed out how October remained one the most erratic months ever, when the country witnessed as high as 36 extremely heavy (more than 204mm rain in 24 hours) events against a normal of 10 or 12 events in the month in recent years. Even during the peak of the monsoon season, in August, the country witnessed 28 such events while June recorded 35 events this year.
“October was highly random and saw exceptional rainfall events over Kerala and Uttarakhand,” said Mohapatra.
Two cyclones, Gulab and Shaheen, seven low-pressure systems against a normal of four and altogether 10 weather systems that squeezed into October alone made last month an exceptionally wet one India has experienced in recent times.
As winter season is nearing, the Met department has said that temperatures over the plains of north India could see marginal fall every time a western disturbance passes.
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