India likely to see normal rainfall in Aug-Sept: IMD

Mangalore Today News Network / News18

New Delhi, Aug 01, 2023: India is expected to record normal rainfall during the second half (August-September period) of the monsoon season following excess precipitation in July, with the IMD saying EL Nino conditions have failed to impact the performance of the annual rain-bearing wind system so far.

 

The India Meteorological Department (IMD) had earlier said El Nino may affect the second half of the southwest monsoon. “Though the country is expected to gauge normal rainfall in August and September, it is likely to lean towards the lower side (94 per cent to 99 per cent) of the normal (422.8 mm)," IMD Director General Mrutyunjay Mohapatra said at a press conference here.

Rainfall recorded between 94 per cent and 106 per cent of the long-period average (LPA), or 50-year average, is considered normal. Normal rainfall is critical for India’s agricultural landscape, with 52 per cent of the net cultivated area relying on it. Additionally, it plays a crucial role in replenishing reservoirs essential for drinking water and power generation throughout the country. Rainfed agriculture accounts for approximately 40 per cent of the country’s total food production, making it a vital contributor to India’s food security and economic stability.

The IMD said normal to above-normal rainfall is very likely over east central India, parts of the east and northeast region and most subdivisions along the Himalayas in August and September. Below-normal rainfall is predicted in most parts of peninsular India and western parts of northwest and central India.

Rainfall in August is expected to be below normal (less than 94 per cent of LPA), but the situation will be comparatively better in September. India logs 254.9 mm of rain in August on average. Though EL Nino — warming of the waters in the Pacific Ocean near South America — has not been able to affect the performance of the monsoon so far, its impact will be visible in the second phase of the monsoon, IMD scientists said.

El Nino is generally associated with the weakening of monsoon winds and dry weather in India. “Currently, weak El Nio conditions are prevailing over the equatorial Pacific region. The latest Monsoon Mission Coupled Forecasting System (MMCFS) and other climate forecasts indicate that El Nino conditions are likely to further intensify and continue up to early next year," the IMD said in a statement.

“The primary reason for below-normal rainfall in August would be El-Nino and the unfavourable phase of Madden Julian Oscillation (MJO), a large-scale intra-seasonal atmospheric disturbance which originates in tropical Africa and travels eastwards," senior IMD scientist D S Pai said.

“In July, favourable phases of MJO helped formation of a number of low-pressure systems over the Bay of Bengal which moved along the monsoon trough and gave good rainfall over central and peninsular India. This factor is going to become unfavourable for at least 10-15 days. So, this aspect will be missing in August," Pai said. The MJO is a large-scale intraseasonal atmospheric disturbance which originates in tropical Africa and travels eastwards. It is like a pulse or wave that lasts for about 30 to 60 days.

During the active phase of the MJO, the atmosphere becomes more favourable for rainfall. This leads to increased cloud cover, stronger winds, and enhanced convective activity, which results in heavier rainfall over the Indian subcontinent.

The IMD said neutral Indian Ocean Dipole (IOD) conditions are prevailing over the Indian Ocean at present and the latest climate model forecast indicates that positive IOD conditions are likely to develop during the remaining part of the monsoon season.

The IOD is defined by the difference in the sea surface temperatures between the western parts of the Indian Ocean near Africa and the eastern parts of the ocean near Indonesia. A positive IOD is considered good for the monsoon. India saw a turnaround in monsoon rains — from a nine per cent deficit in June to 13 per cent excess rain in July, Mohapatra said. However, east and northeast parts of the country gauged the third lowest precipitation (280.9 mm) in the month since 1901, the IMD said.

The region recorded an all-time low of 234.8 mm in July last year. In 1903, it received 249.5 mm of precipitation. At 258.6 mm, northwest India recorded the highest rainfall in July since 2001. Mohapatra said the east and northeast regions have been seeing a decreasing trend in monsoon rains and an increasing trend in mean temperature and minimum temperature. The IMD chief also said India recorded 1,113 heavy rainfall events and 205 extremely heavy rainfall events in July, highest in five years.