Weather inversion in Delhi: Hot, dry wind in time of rain

The dry, hot westerly winds from central Pakistan were blowing at around 20 to 30kmph over not just the Capital but also other parts of northwest India on Wednesday. These winds are especially strong in May and the first half of June before the monsoon arrives, causing temperatures to fall marginally and heat wave conditions to dissipate.

Delhi’s residents enjoyed a (relatively) pleasant May, a time when the infamous Loo blows though the Capital. But on Wednesday, the last day of June, they woke up to the unpleasant, hot wind even as the temperature touched 43.5 degrees Celsius.

The monsoon is yet to set in over Delhi (and not expected to for at least another week), the Capital is experiencing heat waves, and the Loo is here. (AFP)

A meteorologist at a private weather forecaster said these were indeed the Loo, which are uncharacteristically late.

“These are Loo winds which are commonly experienced in May and early June. It’s very unusual to record Loo winds in July or the fag end of June. The wind speed at Palam in Delhi is around 40 to 45 kmph. Till Tuesday the winds were easterly at the lower level and westerly at the higher level so it was a mix of humid and dry winds, making conditions extremely uncomfortable. The temperature is also very high,” said Mahesh Palawat, vice president, climate change and meteorology at Skymet Weather.

The dry, hot westerly winds from central Pakistan were blowing at around 20 to 30kmph over not just the Capital but also other parts of northwest India on Wednesday. These winds are especially strong in May and the first half of June before the monsoon arrives, causing temperatures to fall marginally and heat wave conditions to dissipate.

A severe heatwave in Delhi.

But this year, the seasons seem to have been swapped. The monsoon is yet to set in over Delhi (and not expected to for at least another week), the Capital is experiencing heat waves, and the Loo is here.

“These are winds associated with the heat wave. They are hot dry winds blowing from Pakistan. We cannot say they are unlikely in June because heat waves are recorded in early and mid-June,” said M Mohapatra, director general, India Meteorological Department (IMD).

Only, it is end-June now.

“The pressure gradient is very high so strong westerly winds are blowing. Easterly winds did not set in because the monsoon weakened and did not cover the northwestern region entirely. We are not expecting the monsoon to progress for at least a week,” explained K Sathi Devi, head, national weather forecasting centre, IMD.

The monsoon has weakened significantly since Monday moving into a “break” phase. The normal date for the monsoon to set over Delhi is June 27. It is likely to be delayed till July 7, according to IMD.

As on June 30, the country had recorded 10% excess rains with 14% excess over northwest India; 17% excess over central India; 4% excess over south Peninsula; and 3% excess over east and northeast India.

IMD warned that due to dry westerly and southwesterly winds from Pakistan blowing into northwest India, heat wave conditions are likely over some parts of Punjab, Haryana, Chandigarh, Delhi, Rajasthan, and West Uttar Pradesh till the end of the week.

“As predicted, monsoon enters the break phase with little rains over the country and no signs of revival till July 7. Heavy rains could trigger floods over NE and states like Bihar. Due to dry weather, temps go up over NW India including Delhi with temps >40 C,” tweeted M Rajeevan, secretary, ministry of earth sciences.