50-60% chance of El Niño later this year / by Francisco Blaha

There is a 50-60% chance of an El Niño event forming in middle to late 2017, according to a new Update from the World Meteorological Organization. Following borderline weak La Niña/cool-neutral conditions during the second half of 2016, sea surface temperatures and most atmospheric fields returned to more ENSO-neutral levels in January 2017 that continued to the present.

 from the MetOffice 

from the MetOffice 

However, sea surface temperatures in the far eastern tropical Pacific Ocean increased to 2.0° Celsius or more above average during February and March, creating very heavy rainfall and a trade wind collapse from the Galapagos Islands to the coasts of Ecuador and Peru. This localised warming – known in Peru as a “coastal El Niño” - is different from the more broadly known El Niño warming pattern, but its impacts on the affected areas were just as big.

Many of the climate models surveyed indicate that basin-wide neutral conditions will persist through to June 2017. The subsequent development of an El Niño during the second half of 2017 is more likely than the continuation of neutral conditions. The emergence of La Niña appears very unlikely, according to the Update, which is a consensus-based product, based on contributions from leading centres around the world that monitor and predict this phenomenon, and expert assessment of the results of climate models.

It should be kept in mind that predictions of ENSO made before May or June for the second half of the year typically have less certainty than outlooks made later in the year.

Normally with El Niño stocks will move towards the east further into Kiribati, Tuvalu, Tokelau and Nauru, as water temperatures changes, and therefore away from fishing grounds of Papua New Guinea, Solomon Islands and Palau.

These changes the logistics of tuna trade since it moves transhipments to the reef lagoons of Tarawa and Kirimati and away from Majuro, Pohnpei and Rabaul. It also diverts processing towards Manta in Ecuador, as the most eastern grounds are at this stage closer to Ecuador than to Thailand or the Philipines.

The effects on regional climate of each El Niño event are never exactly the same: they depend on the intensity of the event, the time of year when it develops and the interaction with other climate patterns.

Below and explanation how the 2015-16 impacted global weather.

Background notes

El Niño is often associated with warm and dry conditions in southern and eastern inland areas of Australia, as well as Indonesia, the Philippines, Malaysia and central Pacific islands. During the northern hemisphere summer season, the Indian monsoon rainfall generally tends to be less than normal. In the northern hemisphere winter, drier than normal conditions are typically observed over south-eastern Africa and northern Brazil.

Wetter than normal conditions are typically observed along the Gulf Coast of the United States, the west coast of tropical South America (Colombia, Ecuador and Peru) and from southern Brazil to central Argentina. Parts of eastern Africa (Kenya, Uganda) also usually receive above-normal rainfall. El Niño is associated with milder winters in north-western Canada and Alaska due to fewer cold air surges from the Arctic – a result of a large-scale region of lower pressure centred on the Gulf of Alaska/North Pacific Ocean.