Heat wave to cool over weekend in north India

THERE IS likely to be a respite soon from the unusually early onslaughtofheatthatiscurrentlyprevailing in many parts of northern and central India. The heat wave is likely to persist no longer than Saturday after which the temperaturesareexpectedtocomedown, according to the Indian Meteorological Department (IMD).

“A western disturbance is developing over the Pakistan-afghanistan region. This is expected toresultinrainsinnorthwestindia from tomorrow (Saturday). It will help in bringing the temperatures down in most of northern and central India,” Mrutyunjay Mohapatra, head of services at IMD, told The Indian Express.

The relatively colder temperatures are likely to persist till April 10, he said.

Thesecondweekofmarchhas been unusually warm this year with average temperatures more than 6-8 degrees Celsius above normal in certain places. The maximum temperatures in some places in Vidarbha, Odisha, West Bengal and Jharkhand crossed 43 degrees Celsius on Thursday. The highest maximum temperature was recorded in Akola in Maharashtra which touched 44 degrees Celsius. Maharashtra has already reported two deaths due to excessive heat.

Mohapatra said high temperatures in central India, through Gujarat and Maharashtra to Madhya Pradesh and Chhattisgarh, in March is not uncommon. But there was an additional local factor this year which strengthened the heat.

“During this time of the year, the sun is directly above central India, somewhere just south of the 20 degree latitude (that passes through northern Maharashtra, Chhattisgarh and Odisha). The wind direction during this time is southerly, from south to north in the south-west direction. So the heat from central India gets transported upwards to Gujarat, Rajasthan, Delhi, Uttar Pradesh and northwest India. This is normal. Some amount of heating is observed during this month every year,” he said.

But the reason for the unusually high temperatures was the build-up of an anti-cyclonic circulation over Maharashtra, that is a localised and temporary phenomenon. It does not happen every year.

“What this circulation is doing is accentuating the southerly winds. This is amplifying the heat transfer from central India to the northern areas, over states like Rajasthan, Delhi and Uttar Pradesh. This is the reason why these areas are feeling unusually warm at this point of the year,” he said.

This heat spell is likely to be broken by the western disturbances in the next couple of days. This is a reference to rain-bearing wind system that originates beyond Afghanistan and Iran, picking up moisture from as far as the Mediterranean Sea, even the Atlantic Ocean. It travels from the northwest direction of India and causes frequent rainfall over Pakistan, north and northwest India, Uttarakhand and some parts of Gangetic plains as well.