Weak westerly winds reducing winter chill in Delhi

Meteorologists have blamed feeble western disturbances and the warm easterly winds for the mercury going north. The MeT department has, however, forecasted strong northwesterly winds from Friday, paving the way for the chill to return to Delhi.

cities Updated: Nov 30, 2018 11:06 IST
HT Correspondent
HT Correspondent
Hindustan Times, New Delhi
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Minimum temperature in Delhi is currently two degrees above the normal. (Sanchit Khanna/HT PHOTO)

This year, with the mercury dipping quite early — the night temperature had dropped to 10.5 degrees Celsius on November 8 — Delhiites were hoping for an early winter onset. But the chill has dissipated over the past few days and the night temperature is presently hovering at above 12 degrees Celsius, which is at least two degrees above normal.

Meteorologists have blamed feeble western disturbances and the warm easterly winds for the mercury going north.

The India Meteorological Department has, however, forecasted strong northwesterly winds from Friday, paving the way for the chill to return.

“The rise in the mercury level is mainly because of two factors. The past few western disturbances, which had hit north and northwest India, were too feeble to trigger the desired snowfall in the upper regions of Himachal Pradesh and in Jammu and Kashmir. As a result, the northwesterly winds were neither cold nor strong. Secondly, we are now witnessing strong easterly winds, which are usually warmer,” BP Yadav, deputy director general of IMD, said.

The temperature in north and northwest India is governed mainly by the western disturbances during the winter. When western disturbances approach, the temperature rises. The mercury level dips when the disturbances trigger snow in the hills and Delhi gets some strong northwesterly winds.

The minimum temperature had dropped to 10.5 degrees Celsius on November 8 after a western disturbance had triggered snowfall in the hills. Thereafter, it shot up to 17.6 degrees on November 14. On November 25, the mercury dipped to 10.4 degrees Celsius again – the coldest night of the season so far.

Even though winters were warmer in 2017 and 2016, Delhi had experienced much lower night temperature in November during the last two winters.

In 2017, the night temperature had dropped to 7.6 degrees Celsius on November 24 and in 2016, it had dropped to 9.7 on November 29. The IMD considers December and January as the winter months in Northwest India.

On Thursday, the minimum temperature was 12.2 degrees Celsius, two degrees above normal. The maximum temperature was 26.2 degrees Celsius, one degree above normal.

“Even though the warmer easterly winds were dominant over the past two days, northwestern winds are likely to pick up speed over the next 48 hours. We are expecting the night temperature to drop to around 10 degrees Celsius over the weekend,” Yadav said.

IMD scientists have forecasted that winter over north India would be normal this year while peninsular India would encounter an ‘above normal’ or warmer winter.

“Winter in north and north eastern parts of India is expected to be normal this year with deviation of -0.5 to +0.5 on either side. There could be a few spells of cold wave. In the rest of the country, including peninsular India, east coast and east central India, winter would be above normal or warmer than normal with deviation of 0.5 – 1 degree on either side,” KJ Ramesh, director general, IMD, said.

The IMD is expected to come up with its winter forecast for the months of December, January and February in the first week of December.

First Published: Nov 30, 2018 11:05 IST