La Nina watch is ON and is expected to continue. Equatorial Sea Surface Temperatures (ESST) are below the average from the West Central to East-Central Pacific Ocean. La Nina is likely to continue through the northern hemisphere winter 20-21 with 95% chance during January to March. Potential transition is expected during springe 2021 with a 55% chance of turning neutral from April to June.
ENSO is the oscillation between El Nino and La Nina states in the Pacific region. It carries the potential of impacting weather globally with a drier season for some and deluge for others. La Nina is presently at its peak and indicates a return to neutral by May 2021. Water bodies keep responding with a lag and therefore La Nina effect will remain even after it starts weakening.
Presently it is 100% La Nina and neutral starts surfacing from February onward at the expense of La Nina. El Nino continues to have ‘No Show’ till May or June and thereafter grows marginally to a maximum of 20% through the Monsoon 2021. La Nina pattern appears to be dubious with a gradual drop till June and arise again. This trend needs to be rechecked for sustenance with the next plot in February 2021.
The Nino Indices continue to be sufficiently negative all across the Pacific Ocean. Nino 3.4, the marker for El Nino and La Nina remains below 1°C. Rise and fall of these values are mostly gradual as water bodies retain the memory and release is very gentle.
Sea Surface Temperatures (SST) in the Indian Ocean are warmer than average in the Southern Hemisphere. Compared to 2 weeks ago, anomalies have strengthened slightly. It is too early to talk about IOD as the Indian Ocean Dipole events are typically unable to form between December and April because the monsoon trough remains south over the tropical Indian Ocean. The latest value of the IOD index to 17th January is -0.4°C.
Indian Monsoon has a strong connection with the Pacific warming and cooling. Warming leads to El Nino corrupting the seasonal rainfall and conversely, the cooler Pacific aligns for favourable monsoon. Still, a long way to go for the SST’s and thermocline to become steady and stabilize. IOD values are more consequential May onward.