Most parts of northwestern India will have to wait till the second week of July for the onset of southwest monsoon even as the country as a whole is expected to receive 94 to 106 per cent of normal rainfall during the month, said India Meteorology Department (IMD) Director-General – Meteorology Mrutyunjay Mohapatra said on Thursday.

The long period average (1961-2010) of monsoon rainfall during July month is 28.5 centimetres.

People living in Delhi, Haryana, Punjab and parts of Rajasthan and Uttar Pradesh cannot expect a respite from heatwave conditions for a few days. Maximum temperatures in these regions are 6-8 degrees Celsius higher than the normal. According to Mohapatra, even though there would be a slight drop in maximum temperature over a couple days, the physical discomfort will continue to be there because higher humidity levels.

This year, IMD has adopted a new strategy for issuing monthly and seasonal operational forecasts for the southwest monsoon rainfall over the country by modifying the existing two stage forecasting strategy. The new strategy is based on the existing statistical forecasting system and the newly developed Multi-Model Ensemble (MME) based forecasting system.

10% more rainfall

IMD said during the month of June, the country received 10 per cent more rainfall than normal, even though the rains were deficient in many regions such as several northeast States, Kerala, coastal Andhra Pradesh and Saurashtra in Gujarat. According to IMD, forecasts show that the formation of low pressure systems over north Bay of Bengal is unlikely till July 7 and as a result, subdued rainfall activity is expected over northwest, central and western parts of peninsular India during the next 7 days. However, it did not rule out heavy rainfall spell over northeast India, Bihar and eastern Uttar Pradesh till July 7 because of strong moist southwesterly winds at lower tropospheric levels from the Bay of Bengal.

According to Mohapatra, the latest global model forecasts indicate that the prevailing neutral El Nino-Southern Oscillation (ENSO) conditions are likely to continue over the equatorial Pacific Ocean and that there is enhanced possibility of development of negative Indian Ocean Dipole (IOD) conditions over the Indian Ocean during July to September 2021. “As sea surface temperature (SST) conditions over the Pacific and the Indian Oceans are known to have strong influence on Indian monsoon, IMD is carefully monitoring the evolution of sea surface conditions over these Ocean basins,” he said.

As the delay in monsoon onset is expected to impact agricultural operations such as sowing and transplanting in the northwestern parts of the country, it advised farmers to schedule irrigation for crops. He also said that the early sown crops in the region would also need protective irrigation to conserve soil moisture as well as to prevent evaporation.

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