Heavy rains over Himachal, Uttarakhand due to clash of easterly and westerly winds: Meteorologists

New Delhi: Heavy overnight rains that wreaked havoc in parts of Himachal Pradesh and Uttarakhand were triggered by a "violent interaction" between dry westerly winds and moisture-laden easterlies, meteorologists said on Tuesday.

The overnight downpour swept away at least five people and stranded over 500 in Dehradun and adjoining areas. In Himachal's Mandi, three members of a family died as landslides and flash floods submerged a bus stand.

C S Tomar, head of the India Meteorological Department's regional centre in Dehradun, said the incessant rains in Uttarakhand and Himachal were caused by a confluence of dry westerlies and moist easterlies and that the interaction is expected to continue for the next 24 hours. Mahesh Palawat, vice president (meteorology) at private forecaster Skymet, said no major weather system was present in the region.

"The rains were a result of violent interaction between warm and dry winds due to an anti-cyclone near Rajasthan and humid easterly winds," he said.

This monsoon, 232 people have died in rain-related incidents in Himachal Pradesh, where 46 cloudbursts, 97 flash floods and 140 landslides have caused losses worth Rs 4,504 crore, officials said.

The IMD has not confirmed the cloudburst figures.

Rainfall has been unusually high across north India. Uttarakhand has received 1,343.2 mm of rain so far, 22 per cent above normal, while Himachal has recorded 1,010.9 mm, an excess of 46 per cent.

The IMD said the southwest monsoon, which began withdrawing from northwest India on September 14, three days ahead of schedule, has now retreated from more parts of Rajasthan, Haryana and Punjab.

The season has seen extreme events across regions. Punjab reported its worst floods in decades, while cloudbursts and flash floods repeatedly battered the Himalayan states.

The IMD attributed the surplus rain to active monsoon conditions supported by frequent western disturbances that enhanced rainfall over the region.

Central India has recorded 1002 mm of rainfall so far, 10 per cent higher than the normal of 906.8 mm, while the southern peninsula has gauged 7 per cent more rainfall than the normal of 631.5 mm.

East and northeast India has recorded 998.8 mm of rainfall, 19 per cent below the normal of 1233.9 mm.

In May, the IMD had forecast that India is likely to receive 106 per cent of the long-period average rainfall of 87 cm during the June-September monsoon season.

Rainfall between 96 and 104 per cent of this 50-year average is considered 'normal'.