Why North India is facing unusually heavy rains, explained
India has seen a surge in monsoon rainfall, resulting in a 2% excess rainfall over the country on July 9.
New Delhi: In the past two days, an interaction between a western disturbance and the monsoon trough led to extremely heavy rainfall over Himachal Pradesh, Uttarakhand, Punjab and Haryana, causing landslides, flash floods, widespread damage to highways and other infrastructure.
From a 10% deficiency in rainfall till end of June, the monsoon’s surge over the west coast and parts of northern India in the past week has led to a 2% excess rainfall over the country on July 9, according to the India Meteorological Department.
Read here: Delhi-NCR inundated after heavy showers, civic agencies in damage control mode
There is 59% excess rainfall over northwest India; 4% excess over central India; 23% deficiency over peninsular India and 17% deficiency over east and northeast India, the weather office said.
There was record rainfall over Chandigarh at 32 cm; Ambala 22 cm; Delhi 15 cm; Nangal 28 cm; and Ropar 27 cm, among several other places in Haryana and Punjab between Saturday and Sunday, leading to severe flooding. Himachal Pradesh’s Bhuntar recorded 10 cm and Mandi recorded 8 cm rain until 8.30 am on Sunday.
Himachal Pradesh as a whole recorded 103.8 mm rainfall between Saturday and Sunday morning against a normal of 8 mm, which makes it 1,193% excess rainfall. Similarly, Punjab recorded 57.5 mm against the normal of 4.6 mm rainfall, making it 1,151% excess for the day.
Between 8.30 am on Sunday and 2.30 pm on Sunday, Shimla recorded 5.5 cm of rainfall; Kangra 5.9 cm; Chamba 5.6 cm; Chandigarh 6.3 cm; Patiala 6.1 cm; and Ambala 4.1 cm, among others.
Read here: Record rain batters Delhi, rivers in spate across northern India
The heavy rainfall is due to an interaction between a western disturbance and the monsoon, said M Mohapatra, director general of the weather bureau. “The interaction is causing heavy to very heavy rainfall over Jammu and Kashmir, Himachal Pradesh, north Punjab and Haryana, Uttarakhand. As forecast by us that there will be good rainfall in July, we have covered the rainfall deficit now,” he said. “In the past nine days, rainfall was 24% excess for the period in July. Rainfall will gradually reduce over these states from tomorrow onwards.”
“Recent Himachal Pradesh floods remind us of the 2013 Uttarakhand floods with similar synoptic conditions. An active monsoon with strong low level easterlies bringing plenty of moisture, supported by upper level divergence due to an east-ward moving trough. These are predictable,” said M Rajeevan, former secretary, ministry of earth sciences.
“Recent heavy rains & flash floods remind us one of important impacts of climate change on monsoon “ It rains fewer hours, but when it rains, it rains very heavily” Our forewarning systems & mitigation should further improve This can happen anywhere,” he tweeted.
“Intense rainfall will continue over Himachal Pradesh, Uttarakhand and the northwestern plains for at least the next 24 hours. It will reduce gradually thereafter but is likely to continue over Uttarakhand, Uttar Pradesh and parts of Bihar. The monsoon trough is shifting to the Indo-Gangetic Plains. The current intense spell was mainly because of a western disturbance interacted with the trough. Normal rainfall spells will continue over northwest India thereafter,” said Mahesh Palawat, vice president, climate change and meteorology at Skymet Weather Services, a private forecaster.
"In a changing climate, we see that hilly areas and surroundings - whether it's the Himalayan foothills or the Western Ghats - are particularly susceptible to heavy rains and landslides. Due to global warming, there's extra moisture, and the hills stop this moisture flow and lift it, which comes down as heavy rains. Some of the regions over India where extreme rains have increased are such places where the rains happen due to orographic lifting," said Roxy Mathew Koll, climate scientist at Indian Institute of Tropical Meteorology.
"Flash floods due to cloudbursts and extreme rains are difficult to predict. We should monitor these events closely and identify areas prone to flashfloods. We will have to depend on radars in such hazardous environments to monitor and forecast these events. With a radar, the maximum lead time that we could get is about 3 hours before such an event. We should also check the land use changes and development activities that might have aggravated these flashfloods," he added.
Light to moderate fairly widespread to widespread rainfall with isolated heavy to very heavy rainfall is very likely Western Himalayan Region, Punjab, Haryana-Chandigarh-Delhi, Rajasthan during July 9 and 10 and Uttar Pradesh during next 5 days. Isolated extremely heavy rainfall is also very likely Uttarakhand, Himachal Pradesh and adjoining districts of Punjab, Haryana-Chandigarh on July 9. Isolated heavy to very heavy rainfall likely over Uttar Pradesh during July 10 to 13.
Over west India, light to moderate widespread rainfall with isolated heavy rainfall is very likely to continue over Konkan, Goa, ghat areas of Madhya Maharashtra and Gujarat during next 3 days and decrease thereafter. Over east and adjoining northeast India, widespread light/moderate rainfall with isolated heavy to very heavy rainfall very likely over sub-Himalayan West Bengal, Sikkim, Assam, Meghalaya, Arunachal Pradesh, Nagaland, Manipur during next 5 days.
Read here: Heavy rainfall alert for north India: Himachal Pradesh, Punjab, Delhi to witness downpour on Monday
Isolated heavy rainfall likely over Odisha during next 5 days; Jharkhand during July 10 and 12. Over Central India, moderate, widespread rainfall with isolated heavy rainfall is likely over the region during next 5 days. Isolated heavy to very heavy rainfall is also likely over West Madhya Pradesh during July 9 and 10. Over South India, light to moderate widespread rainfall with isolated heavy rainfall is likely to over Coastal Karnataka and Kerala during next five days.
