India's south-west monsoon is showing signs of strain, with the country recording a 28 per cent rainfall deficit so far this season as an unusual atmospheric pattern slows its progress and suppresses widespread rain. According to the latest India Meteorological Department data, the country received 34.3 mm of rainfall between 4 June and 14 June against a long-term average of 47.7 mm. Analysis at district level shows that huge portions of central, east and peninsular India have received deficient rainfall, while very few areas have seen an excess.
This is happening despite the advance that monsoon made into some areas of south and central India in the past few days. The meteorological community explains that this delay does not arise from a deficit of moisture, but rather due to the presence of an upper atmospheric war going on in the region. The key to the current situation is the shift towards the South in the position of the west wind jet, an upper atmospheric wind stream that is much further to the South than usual.
This has hindered the development of the East wind jet, which plays an important role in the monsoon formation process. Without a strong steering mechanism, rain-bearing systems remain weak or are confined to limited areas instead of pushing moisture deep into the country. The impact is being felt acutely across central India, eastern states, and parts of the southern peninsula, where dry spells have become increasingly common during a period that normally sees expanding monsoon activity. In contrast, a few isolated districts in north-west India have received brief spells of rain driven by localised weather disturbances.
The current deficit is causing concern among meteorologists because it appears more severe than many seasonal forecasts issued in May had anticipated. Most long-range models had projected a healthy start to the monsoon season, supported by favourable ocean conditions. Instead, the atmosphere has thrown up an unexpected obstacle.
There is, however, some optimism for the second half of June. Weather models indicate that the upper-level easterly jet could strengthen after June 20, helping to restore the monsoon's momentum. If such a change takes place, then it may be possible that those rain systems that used to bring rains to the Bay of Bengal might come inland again, thus making the monsoon re-organise itself and move around the country. It will remain to be seen how things work out in the coming days and whether the monsoon will catch up on its lagged schedule.
Also read: Rains bring relief in Delhi from heat, temperature plummets
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