Above normal rainfall likely in Sept, says IMD
NEW DELHI: There is likely to be above normal rainfall activity at over 110% of long period average in September, the India Meteorological Department (IMD) said in its monsoon monthly forecast on Wednesday.
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.
Because above normal rainfall is expected in September, the current monsoon rain deficiency of 9% over the country is likely to decrease and hence overall monsoon rain (June 1 to September 30) is likely to be in the “lower end of normal category,” the forecast said. The LPA of rainfall during September based on the data of 1961-2010 is about 170 mm.
IMD forecast normal rain in August over the country as a whole at 94 to 106 % of LPA. But during August there has been a 24% deficiency due to a longsubdued monsoon phase till around September 17. In its longrange forecast, IMD said southwest monsoon seasonal rain (June to September) over the country as a whole is likely to be normal (96 to 104 % of LPA) at about 101% of the LPA with a model error of ±4%. This, however, has been downgraded to lower end of the normal category on Wednesday.
IMD on Wednesday acknowledged that the multi model ensemble forecasting system couldn’t pick up the magnitude of rainfall in August. “Though the models partially picked up the spatial pattern of rains in August, it couldn’t pick up the magnitude of rain in August. We will examine this and endeavour to improve the output. We have taken note of this,” said M Mohapatra, director general, IMD.
The model also couldn’t capture severe rainfall deficiency over Gujarat and Odisha also.
The MME model uses outputs from 5 best coupled global climate models to forecast.
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, Mohapatra said.
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 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.