Normal summer monsoon expected in 2018 as El Nino-like situation unlikely: IMD

The possibility of El Nino can be ruled out, at least till August this year, according to the India Meteorological Department’s (IMD) recent El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) Bulletin.

According to the IMD experts, an El Nino-like situation is unlikely for the better part of this year, which indicates a normal monsoon in 2018, if other weather parameters work in favour.

The bulletin also observed that La Nina conditions are expected to prevail till June 2018. Currently, such conditions prevail over the equatorial Pacific Ocean. There is a possibility of La Nina conditions prevailing till April, May and June 2018, following which neutral conditions (when there is neither El Nino nor La Nina) will become evident in June, July and August—the first three months of monsoon.

While the absence of El Nino means no negative impact on Indian monsoon, the fact that La Nina will weaken after June eliminates chances of above-normal rain during monsoon.

Besides El Nino and La Nina, the Indian Ocean Dipole (IOD) also has a strong influence on the Indian summer monsoon. An IOD can either augment or weaken the impact of El Nino on Indian monsoon. While a positive IOD can bring good rains to India despite an El Nino year, negative IOD leads to more monsoon break days.

According to IMD, the probability forecast for IOD indicates almost equal probabilities for positive, neutral and negative IOD conditions for the coming seasons. A positive IOD occurs when sea surface temperature is higher than normal in the Arabian Sea and less than normal in the tropical eastern Indian Ocean. The opposite is true in case of a negative IOD.