The country is likely to face a deficient monsoon but Bihar and some parts of eastern India could be slightly better off.
The forecast for countrywide monsoon rainfall this year is 91 per cent. But at the Patna meteorological centre, the weatherman claims the state is expected to receive 93 per cent rain this monsoon. The long-range forecast for the country has an error margin of give or take five per cent and for the state seven per cent. Monsoon is expected to hit Kerala on June 1.
A normal or surplus monsoon is anticipated in the state, after deficient rainfall in the past three years. The state received 17 per cent deficient rainfall last year (2014). It was even worse in 2013 with a 30 per cent deficient rainfall, the lowest in the past 10 years. In 2012, there was 20 per cent deficient rainfall. (See graphic)
Deliberating on the expected rainfall in the state, a senior meteorologist at Patna meteorological centre told The Telegraph: "The long-range forecast for the country is a below normal rainfall because of comparatively lower sea-surface temperature, but monsoon rainfall in eastern India is largely influenced by local weather factors over the Bay of Bengal, including monsoon depression. Based on initial assessment, the forecast for monsoon rainfall in Bihar and other parts of eastern India is likely to be 93 (+/-) 7 per cent - slightly higher than the long range forecast for the country (91 +/- 5 per cent)."
Meteorologists, however, added that a final figure on the expected monsoon rainfall in the state is still to come. Normally, the India Meteorological Department (IMD) releases region-wise forecasts - northwest, northeast, central and south India - slightly before the onset of monsoon in June. Bihar comes under northeast region as per IMD standards.
IMD, in its initial, long-range monsoon forecast on April 22, had stated that the country as a whole is expected to receive 91 (+/-) 5 per cent rainfall. The below normal rainfall was attributed to the El Niño weather phenomenon. El Niño - a Spanish word for Christ Child - is an abnormal warming of water in the equatorial Pacific Ocean every three to five years that can last up to 18 months. This has been associated in the past with poor rainfall in South Asia. "The suitable sea surface temperature for normal monsoon rainfall in India is 27 degrees Celsius in the Indian Ocean. However, the ongoing observations are indicating comparatively lower sea surface temperature, which in turn is expected to lead to reduced monsoon rainfall in the country," said the IMD official.
The official added that it is because of the less warm sea surface or the influence of El Niño that pre-monsoon cyclonic activities are not occurring in the Bay of Bengal or Indian Ocean. "Whatever rainfall has been observed in the region over the past few weeks are only Nor'westers - typical thunderstorm activities in summer season. But there has hardly been any cyclonic activity even though onset of monsoon is around a month away," the IMD official said.
Met experts, however, claim that occurrence of El Niño does not necessarily mean it would lead to drought conditions in Bihar. "Monsoon depressions mostly lead to heavy rainfall within three to four days, which compensates for rainfall deficiency in a localised manner. Normally, 10 to 11 depressions form over the Bay of Bengal during monsoon months - June to September," said Pradhan Parthasarthy, head at centre for environmental sciences at Central University of South Bihar.