When it rains... Cherrapunji gets 3rd wettest day in 122 yrs
NEW DELHI: Cherrapunji in Meghalaya, once the wettest place in India, recorded 97 cm rainfall in the 24 hours ending Friday morning, the third highest quantum of rainfall recorded in 24 hours in the past 122 years. The highest, 156.3 cm, was recorded in Cherrapunji exactly 27 years ago, on June 16, 1995. The only time before that the town saw rainfall of this quantum was in 1956 when 97.2 cm of rain was recorded on June 5.
While the area received 185 cm rain in the last 72 hours, the India Meteorological Department (IMD) said it recorded 330cm rain since June 11.
Mawsynram, now the wettest place in India, also in East Khasi Hills recorded 71 cm, the fifth highest rainfall for 24 hours on June 15. The highest rainfall record for Mawsynram is 94.5 cm recorded on June 7, 1966. Several stations in the East Khasi Hills saw rainfall records tumble in the past three to four days as abundant moisture from Bay of Bengal and Arabian Sea hit the Eastern Himalayas bringing extremely heavy rain to parts of Meghalaya and Assam.
IMD categorises rainfall in excess of 20 cm in a 24 hour window as extremely heavy rain. Cherrapunji and Mawsynram have been recording three to five times that. IMD is now trying to document the amount of rain these stations received every hour to verify if the rainfall events can be categorised as cloudbursts. If 10 cm rainfall is received at a station in one hour, the rain event is termed as a cloudburst.
“Southerly and southwesterly winds have been hitting the Eastern Himalayas for the past one week. Copious amounts of moisture from Arabian Sea and Bay of Bengal are landing up in that region. There is orography which can cause rain. There are very strong winds also and Cherrapunji is on the windward side. We can expect extremely heavy rains for the next two days also but I think the peak rainfall period is over. From June 21, we are expecting rainfall activity to spread eastwards covering Bihar, West Bengal etc,” explained RK Jenamani, senior scientist, national weather forecasting centre of IMD.
“There is a trough extending from northern plains up to Nagaland. There is a lot of moisture feeding that area from Bay of Bengal. The remnant of a western disturbance is also reaching Assam and Meghalaya. In the southern parts of northeast India, such obstruction which can hold the moisture is not there so very heavy rain is not recorded there,” added Mahesh Palawat, vice president, climate change and meteorology at Skymet Weather.
“Environmental conditions favourable for extremely heavy downpour. South-westerly winds were moving towards Garo, Khasi and Jaintia hills from Bay of Bengal. The winds move up to the top of the hills. This is called orographic uplifting of air which can cause a sudden and very heavy downpour. In these regions such downpour can be expected but of course we did not forecast that rainfall will be over 90 cm. We had forecast extremely heavy rainfall. I cannot immediately say if this is due to climate crisis. Extreme rainfall events are going up and they will continue to increase due to global warming,” explained M Mohapatra, director general, IMD.
Overall, monsoon rains have also picked up over the country. There was 32% rain deficiency on June 15 which was reduced to 18% deficiency on June 17. Monsoon has further advanced into remaining parts of Sub- Himalayan West Bengal and some more parts of Bihar. Conditions are favourable for further advance of monsoon into some more parts during next three days.