Strong showers on weekend may help cut rain deficit: IMD

Despite a slow start to the monsoon in the Capital, a probable spell of heavy showers over the weekend is likely to help the city cover its rainfall deficiency for July significantly, the weather office said on Friday

Despite a slow start to the monsoon in the Capital, a probable spell of heavy showers over the weekend is likely to help the city cover its rainfall deficiency for July significantly, the weather office said on Friday.

A motorist trying to start a stalled motorcycle on NH24 during heavy rain in New Delhi, (Raj K Raj / Hindustan Times)

The city received strong showers for two days, as the monsoon arrived on July 13, 16 days behind schedule. However, since Thursday, the showers have mostly halted, and Delhi has seen only traces of rain. The India Meteorological Department, which got a series of predictions wrong over the arrival of the monsoon in the last month, has now forecast heavy rainfall over the weekend and issued an “orange” alert.

According to IMD, the monsoon season officially lasts from June 1 to September 30. “While the usual monsoon onset date in Delhi and NCR is June 27, the season’s maximum rainfall activity is observed between July 10 and end-August. Though rains continue in September as well, their intensity and continuity reduce. Like the first two days of monsoon [in the city, between July 13 and 14], if we get a few more such spells, the deficit for July will be covered,” said Kuldeep Srivastava, head of IMD’s regional weather forecasting centre. The Safdarjung observatory, the official marker for the city’s weather, received only traces (up to 2.4mm) of rainfall on Thursday and Friday. Additionally, the lack of rain has led to hot and humid days.

On Friday, the maximum temperature was 37.8 degrees Celsius, three notches above the season’s normal, and up from 36.6°C on Thursday.

Independent weather forecasters said that the withdrawal of monsoon may be late. Delhi received only 33% of its usual rainfall on July 13, the day monsoon arrived. This has now gone up to around 50%, and the shortfall may get covered with a good spell of rain expected between July 18 and July 21.

Mahesh Palawat, vice-president (meteorology and climate change) at Skymet Weather, a private forecaster, said that while Delhi is likely to cover a large part of its rainfall deficit in the next four days, July is still likely to record only “near normal” monsoon showers.

“Delhi might still record a deficit by July-end. We are, however, likely to see good rains in August, and there is a possibility that monsoon withdraws late this year,” he said.

IMD officials, however, said it is “too early” to predict the withdrawal of the monsoon, since long-range forecasts are generally inaccurate.

Early or late withdrawal of the monsoon doesn’t necessarily depend on the date of the onset. Last year, the monsoon arrived two days ahead of schedule (on June 25) but withdrew on September 25, even as most of that month saw little rain. “Similarly in 2019, monsoon arrived slightly behind schedule (July 5) but withdrew on October 8,” said a senior IMD official.

According to IMD officials, for the monsoon to be considered normal, cumulative rainfall received for the monsoon season must be 650 mm (or 65 cm). “If the total rainfall received is 20% less than normal, it is considered ‘below normal’,” the official said.