August a month of fluctuations for Delhi weather

The frequency and intensity of the weather systems formed in the Bay of Bengal has been low this monsoon. MAHESH PALAWAT, vice-president, Skymet

NEW DELHI: August has been a month of extremes for Delhi, said weather experts. Data from the India Meteorological Department (IMD) for the 29 days of August so far shows that from having a monthly rain deficit of 60%, the city received 11% surplus rain before returning to an 11% deficit as on Sunday. But so far, the city has received just nine rainy days (rainfall above 0.16mm) this month, lower than usual for August, according to data from the weather office.

IMD data shows the first half of August was largely dry, receiving less than half the normal rain the city usually gets during this time of the year, including a partial break phase that lasted for 10 days.

The break ended with the city landing the wettest day of the season on August 21, receiving a record 138.8mm rainfall in a single day, which was the highest for the month in 14 years and the second highest since 1961. Within three days, however, the wet spell made way for another dry spell from August 25-28.

On Sunday too, the Safdarjung observatory, which is considered representative of the Capital’s weather, did not receive any rain till 5.30pm despite the Met forecasting light, scattered rain.

IMD scientists said that the major reason behind the dry phases was not having an intense monsoon system forming in the Bay of Bengal and the Arabian Sea.

“This year, there was no support in terms of continued easterly winds and moisture from the Bay of Bengal that trigger rain. Last year, we had five such systems forming, which resulted in good rains across the country. This season, we had just two such systems, which were not intense enough to travel up to central and northwest India. This has led to the northwest region experiencing weak monsoon spells,” said RK Jenamani, senior IMD scientist.

Independent weather experts shared a similar view.

“One of the major reason for the weak conditions is that both the frequency and intensity of the weather systems (low-pressure systems) formed in the Bay of Bengal this monsoon has been low. Every year during this season at least four to five such systems are formed, which travel up to central and northwest parts of the country bringing rain. This time only two such weather systems were formed, causing frequent weak phases,” said Mahesh Palawat, vice-president, Skymet, a private weather forecaster.

Until August 20, having received only 63.7mm rainfall, the city stood at a rain deficit of 60%. On August 21, the city recorded 138.8mm rainfall, which pushed the cumulative rainfall count for the month to 211.2mm (on August 22) against the normal count of 190.2 mm, reaching a surplus of 11%.

It was followed by light rain over the following three days, after which the city again ran into a dry spell.

On August 29, the city again stood at a monthly rain deficit, this time of 11%. From August 1-29, the city received 214.5mm rainfall, as against the normal count of 241.9 mm.

IMD scientists say normally August brings the maximum monsoon rain to Delhi with a total monthly count of 247.7mm.

“August may end with a slight deficit, as just two more days are left for it to be over and only light rain is expected over the next couple of days. There has been rain in some parts of Delhi, but it hasn’t been observed at Safdarjung Observatory. The city is likely to get patchy rain between August 30 and September 2,” said a senior IMD official.