El Niño finally made an appearance last week as equatorial sea surface temperatures (SST) qualified the criteria of being above the threshold value of 0.5°C for overlapping 3 months for five consecutive episodes. This week also, SSTs continued to be above average across most of the Pacific Ocean, without any variation since the last week.
A decline in the SSTs was seen last week, particularly in the Nino index of 3.4, which is the area of concern for Indian region.
However, they are still well-above the threshold value and that this minute drop is considered to be normal.
The probability of EL Niño conditions is over 60% through Summer 2019 as well through the Monsoon months. Thereafter declining but would remain as high as 50% during the winter months.
Kinds of El Niño and impact on Monsoon 2019
What is the main cause of the worry is the kind of El Niño. There are several types of El Niño that have different impact on the season:
- Normal El Niño: This is most common form that we get to see. During this situation, we see nearly uniform warming of entire Pacific Ocean
- Canonic El Niño: During this, Nino 1+2 gets warmer much earlier than Nino 3.4 region
- Modoki El Niño: This is one of the rare occurrences, during which only central region of Pacific gets warmer, while rest of the areas are relatively cooler
The prevailing El Niño 2019 conditions are looking more like of a Modoki El Niño. As defined above, Central Pacific is at present much warmer than the other areas. During such circumstances, we see volume of warm air rising from central region of Pacific, drifting towards West Pacific that is around South Asia. This warm air pool descends over Southeast Asia, which usually makes a little shift and becomes dominant over the Indian region. Thus, rain in India reduces more than during the standard El Niño event.
The type of El Niño has no relation with its intensity. For instance, a weak El Niño can also result in severe drought during Monsoon, as we have seen in Monsoon 2009 that ended with 78%. Similarly, even a very strong El Niño can lead to mild drought just like in 2015 that saw Monsoon rains at 86%.
El Niño 2019 is also considered to be a milder one. But keeping the type of El Niño i.e. Modoki in mind, we are afraid that impact could be different that we are expecting.
In view of this, Skymet Weather had issued its Monsoon forecast for 2019 to be below normal at 93%, with an error margin of +/-5%.
Any information taken from here should be credited to skymetweather.com