The tropical Pacific atmosphere is consistent with La Nina. Accordingly, La Nina advisory remains in place. However, there are early precursors, showing signs of dwindling by recede of Northern Hemispheric winters. La Nina is expected to continue into the winters, albeit with equitable chance of La Nina and ENSO neutral during Jan-Mar 2023. There is sharp decline likely later and the window Feb-Apr 2023 may assert dominating chance of ENSO neutral.
ENSO : El Nino/La Nina events tend to develop during the period Apr-June and reach their maximum strength during Oct-Feb. Typically, these events persist for 9-12 months, though occasionally last up to 2 years or even more, as is the case in point of triple-dip La Nina still racing in the equatorial Pacific.
Volatility of sea surface temperatures in the tropical equatorial Pacific has increased in the recent past. While, central and western Pacific is having marginal drop, the thermals are shrinking large over the eastern Pacific closer to Peru coastline.
IOD : Indian Ocean Dipole is neutral. It has very little impact on the climatic conditions over the Indian sub-continent between December to April. Sea Surface Temperatures are mostly close to normal across the Indian Ocean basin. Weak anomalies in some pockets is a routine feature, without any implications. During the neutral phase, water from the Pacific flows between islands of Indonesia, keeping the sea region warm, to the northwest of Australian continent. With this, warm air rises above this area and descends over the western half of the Indian Ocean, generating westerly flow along the equator.
The Indian Ocean Dipole value for the week ending 25th Dec 2022 was -0.07Deg Celsius. It is within neutral bounds of +/- 0.4 degree. It is expected to remain neutral till spring season of Northern Hemisphere.
MJO : Madden Jullian Oscillation is expected to move across the Maritime Continent and Western Pacific region over the coming 2 weeks. It is likely to remain inconsequential for the Indian seas on either side of the coastline.
Though ENSO forecast is available for 10 months but it gets attenuated during the 2nd half of forecast period. Model accuracy for lead time greater than 4 months is generally low at this time of the year. Outlook beyond April is to be treated with caution. Therefore, commenting about Indian Summer Monsoon 2023 will be rather premature and need to wait till spring barrier is reached.
