Country records 11% monsoon rain deficiency; northwest 30% in July
There was a 26% rain deficiency in Delhi from June 1 until Wednesday morning. It was expected to fall by Wednesday evening.Updated: Jul 30, 2020 09:13 IST
Delhi and neighbouring Faridabad on Wednesday received light to heavy rain, India Meteorological Department (IMD) said and added weather stations in the national capital at Safdarjung, Lodhi Road, and the Ridge recorded 9.3 mm, 13 mm and 33.2 mm rainfall. Between 15.4 to 64.5 mm is categorised as moderate.
There was a 26% rain deficiency in Delhi from June 1 until Wednesday morning. It was expected to fall by Wednesday evening. Extremely heavy rain (over 20 cm) was also recorded in parts of Uttarakhand and Uttar Pradesh on Wednesday.
Regional Weather Forecasting Centre head Kuldeep Shrivastava said the monsoon trough is passing very close to Delhi and bringing rain to the city. “The monsoon trough is passing along Ferozepur [Punjab], Hisar, Gurgaon, [Haryana] Daltonganj, Dumka [Jharkhand] and parts of Nagaland.” Shrivastava said moisture incursion from the Arabian Sea and Bay of Bengal was likely to bring rain again on Wednesday night and on Thursday.
The western end of the trough has shifted southwards and is near to its normal position from Ganganagar (Rajasthan) to the Bay of Bengal, IMD said.
IMD said widespread and heavy to very heavy rain is likely in Uttarakhand, Jammu, Uttar Pradesh, Punjab, Haryana, Chandigarh, Delhi, Rajasthan, sub-Himalayan West Bengal, Sikkim, Arunachal Pradesh, Assam, Meghalaya, Madhya Pradesh, Chhattisgarh, Gujarat, Andhra Pradesh, Tamil Nadu, and Kerala on Wednesday and Thursday. Extremely heavy rain (over 20 cm) was likely over places like Kerala.
There has been just 1% excess rain since the beginning of the monsoon on June 1 across the country. Eastern and northeastern India have received 12% excess rainfall. There has been a 20% deficiency in rainfall in northwest India, 2% in central India, and 12% excess over the south peninsula. There is an 11% rain deficiency across the country in July with 30% over northwest India; 7.5% excess over east and northeast India; 20% deficiency over central India and 14.6% excess over the south peninsula.
A good monsoon, which accounts for 70% of India’s annual rainfall, is critical to the fortunes of the agricultural sector on which at least 700 million people are dependent for a livelihood. The monsoon is crucial for the yield of rice, wheat, sugarcane, and oilseeds in a country where farming accounts for about 15% of the economy but employs over half of its people.
“The formation of a cyclonic circulation around the South Bay of Bengal is a sign of weak monsoon. This is possibly the first time in several years…a historical record that there was no low-pressure system forming over the Bay of Bengal in all of July and so rains have been deficient in the core monsoon zone. At least 12 to 15 low-pressure systems form over the Bay of Bengal every monsoon most in July and August. This July rain deficiency is 11%,” said RK Jenamani, senior scientist, National Weather Forecasting Centre.
Low-pressure systems are the main rain-producing systems during monsoon. Their formation depends on dynamics like the interaction of south-westerly and easterly winds, added Jenamani.
IMD has also issued a moderate to severe thunderstorm and lightning warning for Jammu & Kashmir, Ladakh, Gilgit-Baltistan, Muzaffarabad, Himachal Pradesh, Uttarakhand, Uttar Pradesh, Haryana, Chandigarh, Delhi, Bihar, Madhya Pradesh, Telangana, Coastal Andhra Pradesh, Yanam, Tamil Nadu, Puducherry, Karaikal, and Rayalaseema on Thursday.
“I remember 2002 was a very bad year when hardly any low-pressure systems formed. Low-pressure systems over the Bay of Bengal are rain-bearing systems. When they move into the land, they bring a lot of rain so they are critical during monsoon. Along with global features, two local features are critical for the development of low-pressure systems--wind shear (change in wind speed and direction) and moisture,” said SK Dash, professor, Centre for Atmospheric Sciences, Indian Institute of Technology Delhi.