Equatorial sea surface temperatures(SSTs) remain below normal across most of the Pacific Ocean. Since mid-May, below-average SSTs have weakened across most of the equatorial Pacific Ocean.
Key ocean and atmospheric parameters remain compatible with La Nina conditions. A slight weakening of the La Nina component at the cost of ‘neutral’ probability is emerging during the late monsoon months. However, the La Nina advisory remains in place for July 2022.
ENSO: Uncertainty remains over whether La Nina may transition to ENSO-neutral during the monsoon months or weak La Nina may as well continue through the season. All 4 Nino indices are staying below the threshold for a fairly long. However, these markers have not changed at all for the last 2 weeks. The Ocean surface close to the Peru coast continues to be the coolest with a drop of over 1°C, since 03rd April 2022.
IOD: The Indian Ocean Dipole index has been below zero for 8 consecutive weeks. IOD is becoming increasingly -ve over the last few weeks. The index is below the threshold value of -0.4°C for the last 3 weeks. This is aligned with a likely -ve IOD event through the monsoon months and is expected to persist till Nov 2022. A -ve IOD suppresses convective activity over the Arabian Sea and represses the monsoon bursts over the Indian Sub-Continent. The latest IOD index value for the week ending 03rd July 2022 was -0.69°C.
MJO: Madden Julian Oscillation has moved to the maritime continent in phase 4. However, it still remains favourable for enhancing convection over the Bay of Bengal. Already, a pair of cyclonic circulation appeared over the Bay of Bengal in the last one week. Another one is likely around 10-11 July. This will support the active monsoon conditions during the 3rd week of July.
La Nina conditions have prevailed for 2 consecutive years. While back-to-back La Nina events are not uncommon, 3 in a row are scarcely seen. La Nina/ El Nino records have been maintained authentically from 1950 onward. The hat trick of La Nina has occurred thrice since then: 1954-57, 1973-76 and 1998-2001. While even a shadow of La Nina conditions will favour better Southwest Monsoon, -ve IOD event is never seen kindly. The adverse impact of IOD can be partially neutralized by the cool Pacific but not without a struggle in the 2nd half of the season.
