El Nino conditions are building up steadily. Consistent pattern continues to evolve since beginning of the year. Negative sea surface temperature (SST) anomalies have gradually weakened across most of the equatorial Pacific Ocean. Positive SST anomalies have strengthened in the eastern equatorial Pacific. The probability of El Nino is increasing to 50% in May-Jul and later it becomes a commanding category with probability of 60-67% from June-August. ENSO neutral is the next most favoured category with probability in the range of 31-35%. La Nina is getting decimated and remains suppressed through the monsoon season. This means, it is going to be evolving El Nino year.
ENSO : 'Spring Predictability Barrier' makes it harder for the numerical models to deliver accurate forecasts about the post spring season. During the last 4 weeks, +ve SST anomalies have emerged more prominently across the equatorial Pacific Ocean. The sub surface ocean temperatures anomalies of more than 1degree, up to the depth of 200mtr or more is desirable for formation and sustenance of El Nino. All the Nino indices are no longer negative and have warmed up appreciably off the coast of South America.
All indices are expected to turn +ve and incrementally grow in April 2023. However, crossing the threshold mark of +0.5 degree will take time and may roll over to May 2023.
IOD : The Indian Ocean Dipole is currently neutral. The IOD index value for the week ending 02Apr 2023 was +0.29 degree, slight drop from the last week mark of +0.36 degree. Model projections are indicative of gradual rise in the early part of monsoon and commensurate drop during the later half. IOD is unlikely to turn strongly positive to take on evolving El Nino in its backyard. IOD forecast made at this time of the year have very low accuracy. Reliable forecast emerges only after the spring barrier gets over.
MJO : The Madden Jullian Oscillation had weakened considerably last week to become nearly indiscernible. It is likely to gain amplitude during this week while sailing in phase 6&7 over the Western Pacific Ocean. However, strengthening of MJO remains inconsequential for any weather activity over the Indian Seas.
El Nino often cripples monsoon rainfall over Indian sub-continent. It is showing signs of evolving, immediately after cessation of Triple Dip La Nina. El Nino watch is already 'ON' confirming its probability around the monsoon time. It appears to be fairly strong. El Nino has profound effects on global weather pattern as well. Therefore, worries get heightened on account of its impact on Kharif crops across the Indian sub-continent.
