La Nina has developed and is expected to last into next year, affecting temperatures, precipitation and storm patterns in many parts of the world, says World Meteorological Organization (WMO) in its latest report published on October 29, 2020.
This year’s La Niña is expected to be moderate to strong. The last time there was a strong event was in 2010-2011, followed by a moderate event in 2011-2012.
What is La Nina?
- La Nina refers to the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall.
- It usually has the opposite impacts on weather and climate as El Niño, which is the warm phase of the so-called El Niño Southern Oscillation (ENSO).
What will be the impacts?
- La Niña can lead to increased rainfall in Southern Africa and this is indicated by some recent seasonal forecast models.
- It can also affect the South West Indian Ocean Tropical Cyclone season, reducing the intensity.
- Central Asia is likely to see below normal rainfall even earlier than usual.
- Those in the Central and Eastern Pacific may be more susceptible to below normal rainfall, while countries in the South-West Pacific will become more prone to above normal rainfall.
- In previous La Niña events, South Asia has experienced a mix of effects. The latest seasonal outlook provides a similar mixed picture, with dry conditions expected over the next few months in the north of the region while the rest of the region is expected to see near normal conditions.
(Source: WMO)
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