It was a good news the government couldn’t wait to share. Amid prevailing drought and severe drinking water crisis in many parts of the country, the meteorological department Tuesday said this year’s monsoon season was likely to bring very good rainfall.
In its first forecast for this monsoon season, the Indian Meteorological Department (IMD) said rainfall in the four-month period of June to September was likely to be 106 per cent of the long period average (LPA). This LPA, the average of monsoon rain over the 50-year period from 1951 to 2001, comes to 89 cm and is considered normal. So this season, the country as a whole is likely to receive about 94 cm of rainfall.
The forecast is likely to bring widespread cheer in the country, which is reeling under a drought after two successive years of highly deficient rainfall during monsoon season. That was probably the reason the Met department advanced the announcement of its forecast by about two weeks, the earliest it has issued it in the last 10 years. The first forecast for the monsoon is generally issued in the third or fourth week of April. Only once since 2010 has the forecast been announced before April 20. That was in 2011, when it was issued on April 19.
IMD follows up with another detailed forecast at the end of May, when it also predicts regional and monthly distribution of rainfall during the season.
But such was the excitement to share the good news that IMD director general L S Rathore pre-empted the second forecast and said that the rainfall was likely to be evenly distributed over the entire country. In response to specific queries, he said the Marathwada region, which is experiencing the worst impact of drought, was likely to receive good rainfall during the monsoon. Rathore said only the northeastern region and some parts of southeastern peninsular region in Tamil Nadu were likely to receive relatively less rainfall. He also said that all four months were likely to be wet and bring at least normal rainfall.
The monsoon had produced only 88 per cent rain in 2014 and 86 per cent in 2015. The previous time such drought had happened for two successive years was in 1986-87.
The IMD said the forecast was nearly certain, with 94 per cent probability that the rainfall would be least 96 per cent of the LPA. There was only one per cent probability of it being below 90 per cent of the LPA.
The weakening of the El Nino phenomenon in the Pacific Ocean and strengthening of Indian Ocean Dipole are among the main reasons for a strong probability of good rainfall. The El Nino phenomenon, the abnormal heating of sea surface in equatorial Pacific Ocean, was blamed for the sub-normal performance of monsoon rain in the last two years. The El Nino continues to prevail but is showing signs of weakening.
“Analysis of previous data suggests that monsoon season rainfall over the country as a whole was deficient or below normal (less than 96 per cent of LPA) during 65 per cent of El Nino years. However, during 71 per cent of the years followed by El Nino years, monsoon was normal and above (more than 96 per cent of LPA). The latest forecast from the monsoon mission coupled climate model indicates that El Nino condition is likely to weaken to moderate or weak levels during the first half of the monsoon season and ENSO neutral condition is likely to get established thereafter,” the IMD said in its forecast.
ENSO neutral condition refers to the state when the sea surface temperatures in the Pacific Ocean are normal.