The effect of El Nino on Southwest Monsoon remains a contentious issue, though, more often it is linked with poor performance of seasonal rains. El Nino refers to the periodic warming of ocean waters in the east and central equatorial pacific. This phenomenon leads to changes in the wind pattern which in turn impacts weather across large parts of the globe.
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El Nino had started evolving last year during autumn months which ran through the winter season also. Earlier, most weather agencies all over the globe had pronounced 50-60% chances of El Nino, during the Indian summer months. The current status indicates towards a probability of 90% El-Nino during monsoon months. However, it is showing a declining trend, though marginally, dropping from 90 to 60% by year end. Possibly, the El Nino may enter a devolving phase during the latter half of the year. It is important to note that El Nino conditions are to be read carefully along with other oceanic and atmospheric parameters like Indian Ocean Dipole (IOD) which have close linkages with the likely weather pattern and performance of Monsoon. Click here to Know what is Monsoon.
IOD refers to changes in the temperature differences between the western and eastern parts of the Indian Ocean. El Nino along with negative IOD is considered detrimental for Monsoon rains. However, the Indian Ocean this season is responding positively and is warm enough to allay fears of weak Monsoon rains. While the Pacific remains warm, the El Nino remains weak with NINO index barely crossing the threshold value of 0.5 in the last six consecutive overlapping seasons of three months each. The current value for the Feb, Mar, Apr quarter stands at 0.6. This is expected to rise for some time and decrease thereafter. Also, the Southern Oscillation (SO), which is mostly read along with El Nino as ENSO, is neutral. No distress signal is emerging even from another important atmospheric index Madden Julian Oscillation (MJO).
There is no denial that El Nino conditions are prevailing. However, mere occurrence of El Nino, that too with marginal values, need not raise damaging alarms. After all, there are El Nino years when the Monsoon rainfall has remained normal and occasionally above normal too. Skymet expects the NINO index to remain above the threshold value depicting El Nino conditions through the summer months. It is then expected to decrease gradually. Accordingly, Monsoon rains this year are expected to be normal.
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