Monsoon rains 28% above normal; may peter out in August

Bringing relief to the Indian government as well as its people, the monsoon is advancing apace across India; and the India Meteorological Department today predicted above-average rainfall in July, though it will taper off a little in August.

The IMD said that rainfall over the country for the months of July and August would be 'normal' at 96-104 per cent of the long period average (LPA), with a model error of 9 per cent.

However, the development of a weak negative Indian Ocean Dipole (IOD) during the second half of the monsoon (August onwards) could be a matter of concern. The July rainfall would be 101 per cent of the normal and August rains would be 96 per cent of the normal, IMD said.

In its monsoon update, the IMD office has stuck to its April prediction of 98 per cent of the LPA rainfall this season. In its first two weeks, monsoon has covered two-thirds of the country and overall rainfall to date is 28 per cent above the LPA.

The Met office said 78 per cent of the country's 36 sub-divisions have recorded above-average rain so far. "The actual rainfall recorded since 1 June is 65 mm as against the normal of 50.6mm," an analysis released by the IMD from its Pune headquarters said.

While IMD's traditional six-parameter statistical forecasting system has thrown up a 98 per cent LPA monsoon, its experimental forecast system based on the monsoon mission's dynamic prediction system has indicated 108 per cent of LPA for the season, with an error margin of 4 per cent.

The only point of concern is northwest India, which saw the lowest amount of rain across the four meteorological regions in the country last year. This year, the region is expected to receive 94 per cent of normal rainfall.

The prediction for other regions is close to 100 per cent – 98 per cent for both central and northeast India and a good 103 per cent for the peninsular region (which includes Mumbai).

Dr D S Pai, director (long-range forecast), IMD, said a weak La Nina conditions developing in the second half of the monsoon was indicated, which could boost rains in that period. La Nina is the name given to unusual cooling of east central Pacific Ocean waters, which is seen to aid the southwest monsoon, unlike its nasty brother El Nino.

"There is a 65 per cent probability of neutral conditions continuing in the Pacific through the season. However, the probability of a weak La Nina emerging during the latter part of the monsoon season has increased," said Pai.

But the La Nina effect will be counterbalanced by the weak Indian Ocean Dipole, a cooling of western Indian Ocean region that inhibits the monsoon, which is likely to develop towards the second half of the monsoon.

"It is likely to set in towards the end of the monsoon and peak after the season is over. In the event that it becomes strong during the monsoon, it could have a negative impact on the rains. But it appears that it would be weak and hence not have much impact finally," he said.

The IMD has forecast favourable conditions for the monsoon to move into some more parts of Rajasthan, the remaining parts of Madhya Pradesh, Jharkhand and West Bengal and Sikkim and some parts of Bihar and Uttar Pradesh during the next 48 hours.

"Conditions are also favourable for further advance of southwest monsoon into more parts of northwest India, including Delhi, earlier than its normal schedule," the IMD has predicted.

Of the 36 IMD sub-divisions, 27 have reported excess rainfall while another four sub-divisions have recorded normal rains. Two sub-divisions, Gangetic West Bengal and Haryana, have recorded deficient rainfall while another three, Arunachal Pradesh; Assam; and Meghalaya, Nagaland, Manipur, Mizoram and Tripura (MNMMT) have recorded scanty rainfall.

The early onset of the monsoon should cheer farmers, as these are the most critical months for sowing. Around 60 per cent of India's agricultural land remains rain-dependent.