Delhi Receives Little Rain In 10 Days, IMD's Inaccurate Forecasts Leave People Puzzled

The India Meteorological Department (IMD) has struggled this season to make accurate weather predictions for the national capital Delhi.

While the monsoon hit Delhi impressively on June 30, rains have evaded Delhi since then as only 2.6 mm rainfall has been recorded in last 10 days at the Safdarjung Observatory, Delhi's primary weather station.

Though experts acknowledged that providing accurate localised forecasts is a complex process, they said IMD cannot be off the mark repeatedly.

The Safdarjung Observatory has gauged 144.3 mm of rainfall against a normal of 126.7 mm since June 1, when the monsoon season starts. Of this, 117.2 mm came in just 24 hours ending at 8:30 am on July 1.

After the season's first spell of heavy rain on June 30-July 1, the IMD issued an orange alert, warning of moderate rainfall in the city on July 1. A yellow alert was issued for light rain over the next six days.

While just 2 mm of rainfall occurred in the next three days (July 1-3), the IMD on July 4 issued a yellow alert for July 5 and an orange alert for July 6, which was later shifted to July 7.

While Delhi kept waiting for rain, experts attributed the dry spell to the shifting of the monsoon trough towards central India due to the development of a low pressure area over Odisha which subsequently travelled to Gujarat.

"The low pressure area had pulled the trough towards central India, leading to heavy rainfall there," said Mahesh Palawat, vice president (meteorology and climate change), Skymet Weather.

The IMD later predicted "fairly widespread to widespread rainfall activity" over west Uttar Pradesh, Punjab, Haryana, Chandigarh, Delhi and Rajasthan on July 9 and July 10, and issued a yellow alert, warning of moderate rainfall in the capital on Sunday.

But that did not happen either.

Palawat said, "It was expected that the western end of the monsoon trough would again shift towards the north after the low pressure area degenerated. However, the development of a cyclonic circulation over southwest Rajasthan and adjoining parts of south Pakistan in the last 24 hours did not let the monsoon trough come near Delhi and neighbouring areas. It is still stuck south of Delhi and passes through Bikaner and Kota."

Parts of Punjab and Haryana received rainfall due to the convergence of winds —westerly winds in the upper level and easterly winds in the lower level— in that region.

Palawat said there are chances of patchy rainfall or thundershowers as a result of moisture incursion and localised heating on Sunday.

He added that Delhi wwill not get any rain on Monday and Tuesday. He further said rain is likely on July 13-14 after the low pressure area crosses Gujarat and the monsoon trough shifts towards the north.

Madhavan Nair Rajeevan, a former secretary at the Union Ministry of Earth Sciences, said it's okay to get weather forecast wrong "once in a while, but it should not happen often".

He added, "Yellow, red, orange alerts are issued when you are really confident about something which is going to affect people. With the modern technology [available], you have good inputs before you issue alerts. We have improved a lot with time. We should be able to make a good forecast at least two or three days in advance."

Rajeevan further said it could also be a case of over-warning considering Delhi is the national capital and forecasters tend to be cautious. 

He said, "But it can't be a continuous process. You cannot do it every day. If you do, it means you are missing something. I do not want to blame anyone because I do not know the details."

Rajeevan added localised weather forecasts have become complicated because models do not account for pollution, aerosols and land use changes. 

The case of Delhi is not the first time that IMD's forecasts have been questioned by independent experts this season. Earlier, IMD was criticised for declaring monsoon before the criteria set by IMD itself was fulfilled.

Experts highlighted that the monsoon's arrival is announced when eight weather stations in Kerala, Lakshadweep, and Karnataka receive a minimum of 2.5 mm of rainfall for two consecutive days, but only five stations received this on the day of IMD's announcements.

IMD Director General Mrutyunjay Mohapatra said it did not make a "huge difference".

He had told Hindustan Times, "Even if we don’t meet the rainfall criteria for the second day, it doesn’t make a huge difference. The criterion was met on Saturday which is why onset was declared. We cannot expect that the criteria will be met every day. Tomorrow again rainfall will increase."

However, experts said it affects the well-established trend and the reputation of the institution.

"Declaring monsoon based on single day observations amounts to gross violation of standards, never attempted in the past.  Any repute scientific body can ill afford to bend rules and criteria, just to prove the forecast right.  Such a step, if taken knowingly, becomes highly objectionable and if otherwise, amounts to illusion of knowledge," said private weather forecaster Skymet in a statement.   

(With PTI experts)