New Delhi, June 24: Weather scientists today asked the country to brace itself for a below-normal monsoon, raising the possibility that India’s breadbasket states in the northwest could face a meteorological drought.

But agricultural scientists held out some hope, saying the impact on crops would depend on the rainfall distribution over the next three months.

The India Meteorological Department has said rainfall across all of India is likely to be 93 per cent, or below normal, of the long period average, revising its April forecast that had predicted a near-normal 96 per cent rainfall.

The revised forecast relies on six weather conditions, among which four are currently unfavourable for the 2009 monsoon, said Damodar Shivanandan Pai, director of the IMD’s long range forecasting division in Pune.

The new forecast has also thrown up predictions of 81 per cent rain in northern and western states and 92 per cent rain in eastern and northeastern states. Rainfall below 90 per cent of normal is classified as a meteorological drought. The last drought in the country was in 2002.

Scientists pointed out that meteorological drought was different from agricultural drought which would depend on the level of moisture stress that plants in a region would experience. This would in turn depend on the availability of water.

Agrometeorological scientists said 81 per cent of normal rainfall could theoretically affect rice yields in Punjab, Haryana, Uttarakhand and Uttar Pradesh, although the exact impact would depend on the period and duration of dry spells. The Planning Commission tried to allay fears of adverse impact on the economy. (See Business)

“Much of northwestern India is irrigated, and those who can successfully irrigate crops are unlikely to be affected much. But not every farmer is in a position to provide irrigation,” said Kamlesh Kumar Singh, an agricultural scientist at the IMD.

The IMD has also predicted that July would receive 93 per cent of normal rain and August would get 101 per cent. Computational forecasts suggest that atmospheric conditions would lead to a normal rainfall in the northwest during the first fortnight of July.

“We do not expect (rice) sowing operations to be affected, but if a dry spell lasts more than 15 days during the vegetative stage of the plant growth, you could expect some impact,” Singh told The Telegraph.

Singh said how the rainfall is distributed over the next three months would determine its impact on crops.

“A 92 per cent rainfall for eastern and northeastern states is unlikely to have any impact (on crops) if it comes when it is needed,” he said.

Crops such as maize and pulses are not likely to be affected much, he added.

The forecast of 99 per cent rainfall in central India and 93 per cent in the southern states suggests that any rain-bearing low pressure zones that form in the Bay of Bengal are likely to move west, instead of moving northwest.

Scientists said sea surface temperatures over a region of the Pacific Ocean appear to be rising — a phenomenon called El Nino -- which has in previous years been linked to a poor rainfall. Both observations as well as forecasts suggest that there is a high probability (60 per cent) for El Nino conditions to appear during the monsoon season. India has never had excess rainfall during an El Nino year, Pai said.

“This forecast is based on the physics of the atmosphere. Its implications would have to be analysed by appropriate ministries,” said Prithviraj Chavan, minister for science and technology and earth sciences, who formally released the revised forecast.

Scientists believe cyclone Aila which had struck Bengal in May contributed to the poor performance of the monsoon during June. “The cyclone took away the entire energy from the monsoon,” said Pai. “It’s like taking away a bank balance.”

“We had similar situations in 1982, 1987 and in 1991 -- cyclones in May adversely affected the monsoon in June,” Pai said. The monsoon performed poorly in 1982 and in 1987, but 1991 had a normal monsoon.