The first triple-dip La Nina of the 21st century will continue to affect temperature and precipitation patterns. It will also exacerbate drought and flooding in different parts of the world. As per the WMO update, the protracted La Nina conditions which began in September 2020 are still continuing, albeit with a transient and inconsequential break during last year.
ENSO: There is a 75% chance for continuation of La Nina till winter 2023 of the Northern Hemisphere. The probability of transition to ENSO neutral condition by Feb-Apr 2023 is 70% and increases further during the summer months.
Oceanic Nino Index (ONI), the lead indicator of La Nina/El Nino has sustained below the threshold value for a fairly long. Th index has not risen above -0.8deg since August 2022. The principal indicator and monitor of La Nina has again plunged to -1.0deg for the last 2 weeks. Neighbouring Nino 3 region is further cooler at -1.1deg Celsius.
IOD: Indian Ocean Dipole has returned to neutral and turned +ve, albeit marginally, for the 1st time, since May 2022. The index remained in the neutral range (between -0.4 deg and +0.4 deg) for 6 consecutive weeks. The most recent value for the week ending 11 December 2022 was +0.05deg. As the monsoon trough has shifted to Southern Hemisphere, the IOD has hardly any influence on Indian climatic conditions. Such a stalemate continues till the early summers of the Northern Hemisphere ( Mar-Apr 2023). Both, areas of warm and cool anomalies on the eastern and western sides of the Indian Ocean have dissipated in recent weeks. However, IOD is likely to remain +ve, but within the neutral limits, till Apr 2023.
MJO: Madden Jullian Oscillation remained between phase1 &3 over the Indian Ocean. Its amplitude consistently remained small during 1st half of December. Amplitude will rise from 18th Dec onward. This will not hamper oceanic conditions over the Bay of Bengal and the Arabian Sea. Normal northeast monsoon activity is expected during the 2nd half of December, with short breaks in between.
La Nina is a natural and temporary phenomenon, which refers to the large-scale cooling of Sea Surface Temperature in the central and eastern equatorial Pacific Ocean. The continuation of La Nina for the 4th consecutive year does not find recorded in history, since 1950. The longest La Nina event, lasting for 38 months goes back to the '70s, between April 1973 to May 1976, with a transient and minuscule drop for 2 months in 1974.