This is what caused the ‘freak’ dust storm that killed more than 100 people in north, west India

The freakish thunderstorm that and crops in several states in north and north-west India on Wednesday night was produced by a confluence of factors, Met office has said.

A powerful dust storm swept across several parts of western and northern India, killing more than 100 people and injuring hundreds in Uttar Pradesh, Rajasthan and Uttarakhand and leaving a trail of destruction, uprooting trees and disrupting power supply in Punjab, Haryana and Madhya Pradesh as well.

“A western disturbance-induced cyclonic circulation, high moisture brought by easterly winds and the recent spell of unusually high temperatures caused these weather conditions,” Kuldeep Srivastava, a senior official at India Meteorological Department (IMD), said.

A squall line or a chain of thunderstorm clouds emerged on Wednesday afternoon from north Rajasthan to eastern Uttar Pradesh passing over Delhi as well.

“It can be called a freak incident,” Mahesh Palawat, chief meteorologist at Skymet Weather, a private forecaster, said, “dust storms are usually not this intense nor do these systems cover such a large area.”

Two major patches of storm clouds were formed, one originating over western Haryana and another over north Rajasthan. The former was less intense bringing rainfall to Delhi and Haryana but gradually weakening over north Delhi.

The stronger system that developed over northern Rajasthan was fed by high temperatures prevailing in the region the past few days. Parts of Rajasthan saw maximum temperatures touching 45 degrees C. Higher temperatures allow greater retention of moisture and formation of deeper storm clouds capable of bringing more rainfall and generating stronger winds.

This cloud cluster was continuously reinvigorated as it moved eastwards by available moisture travelling as far as eastern Uttar Pradesh wreaking havoc along the way in places such as Dholpur, Alwar and Dausa in Rajasthan, Agra in Uttar Pradesh.

“Local thunderstorm formation is impacted by temperatures,” Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology, said. “All over India temperatures are abnormally high, even if they are not the drivers, they will aggravate the situation by causing the atmosphere to become more unstable.”

Pre-monsoon thunderstorms usually affect northern India in April and May, according to Srivastava,

“We can expect some activity every week to 15 days,” he said.

Temperatures in Delhi dropped by about 5 degrees C as a result of the dust storm and rains.

Maximum temperatures on Thursday in Delhi was around 36-38 degrees C and is expected to climb again from Friday. Maximum temperatures may hit 42 degrees C on Monday but light showers are expected on Tuesday night, Srivastava said.