All eyes are on rainfall activity in September as the India Meteorological Department (IMD) is expecting above normal rainfall at 110 per cent of long period average (LPA) to reduce deficiency and predicted the southwest monsoon is likely to be “around the lower end of the normal” this year. A huge deficit of monsoon rainfall in August may now, however, put it at the “lower end of the normal” with 96% of the LPA. If rainfall activity remains below normal in September, there is a possibility of drought-like situation in the country. Skymet weather, a private forecaster, has earlier predicted below normal rainfall this year.
By August 31, 10 Union Territories / States experienced a rain deficit of 23-52 per cent. Most of these States were in the northeast and northwest regions.
Releasing the forecast for the month of September, IMD Director General Mrutunjay Mohapatra said considering the expected above normal rainfall activity during September, the current deficiency of 9% in seasonal rainfall during June to August is very likely to reduce and accumulated seasonal rainfall from 1 June to 30 September 2021 is very likely to be around the lower end of the normal.
The LPA of rainfall during September based on the data of 1961-2010 is about 170 mm.
As per the latest forecast, the IMD said Above normal rainfall activity is likely over many parts of central India. Normal to below normal rainfall is most likely over many areas of northwest, northeast and southern most parts of peninsular India.
The monsoon was mainly done in by an unexpectedly huge deficit of 24.1 per cent in rainfall during August, normally the second rainiest after July of the four monsoon months. Mostly, August rain deficits are associated with El Nino and negative Indian Ocean Dipole (IOD) events (nine out of 15 years).
Long periods of subdued rain in August and July have impacted agriculture. There is deficiency in sowing in many parts of central India; the rain deficiency over northwest India particularly Haryana, Punjab, Rajasthan, west Uttar Pradesh, west Rajasthan can be dealt with to an extent to availability of irrigation.Monsoon entered a ‘break’ or a ‘partial break’ phase thrice this season, mainly between June 29 and July 11; it was very weak in the first two weeks of August also leading to a significant deficit in rains across the country. While it revived over northwest India on August 19, it weakened again from August 24 onwards and started reviving very gradually from August 29.
According to IMD, the main reasons for subdued monsoon in August is negative Indian Ocean Dipole (IOD) which is normally unfavourable for monsoon; complete absence of formation of monsoon depressions in August (normally at least two depressions form in August); only two low pressure areas formed over Bay of Bengal against a normal of four among others. There was very less typhoon activity over the West Pacific. The remnants of these typhoons move westwards normally and help in creating low pressure areas over Bay of Bengal.
As per IMD website, 10 Union territories / states experienced rain deficit of 23-52 per cent till August 31. Most of these states were in the northeast and northwest regions. Manipur, for instance, reported a 58 per cent deficit rainfall by August-end; Gujarat received 50 per cent less rainfall than normal.
In the eastern region, Odisha experienced 29 per cent deficit rain and Kerala received 22 per cent less rainfall than normal.