Samoa and other Pacific countries can expect stronger trade winds and more rainfall in the coming months as a La Nina forecast has been officially declared.

The declaration was made on Friday afternoon by the Pacific Meteorological Desk Partnership at the Secretariat of the Pacific Regional Environment Programme (S.P.R.E.P). 

It comes amidst heavy downpours in Samoa, which brought flooding and landslides in some parts of the country including Fagaloa. 

La Niña is the name given to the phenomenon where the trade winds become stronger, enhancing the warm pool in the western Pacific and causing the sea surface temperatures in the central and eastern Pacific to become cooler.

"As a result, Pacific islands in the central Pacific region such as Kiribati, Nauru and Tuvalu may experience below normal rainfall during this period, while islands in the south-west Pacific will usually experience higher than normal rainfall, such Fiji, Niue, Palau, Papua New Guinea, Samoa, Solomon Islands, Southern Cook Islands, Tonga and Vanuatu."

La Niña is part of the El Nino Southern Oscillation (E.N.S.O.) which is a major climate driver that influences normal rainfall, temperature and sea level patterns across the Pacific. E.N.S.O. is a slow onset event whereby the impacts are not felt immediately by Pacific islands but gradually over time, unlike events such as tropical cyclones, whereby the impacts are felt as soon as the events occur.

La Niña persists for at least five months. 

“These phenomenon may sound scientific, but the fact is that these terms and what they are will have direct impact on our lives in the Pacific, they will affect our food crops, our hygiene in the time of COVID-19 and our safety with the impacts of tropical cyclone season and floods or landslides in some parts of the region and potential drought in others,” said Tagaloa Cooper, the S.P.R.E.P. Director of Climate Change Resilience.

“We must all make an effort to know what is happening with our weather and climate and prepare ourselves for what may come, the more we can prepare, the more resilient we will be."

Countries are encouraged to seek more information from their local meteorological services or weather offices and national Disaster management offices on latest development on the La Niña event as well as specific actions on how to minimise the negative impacts that may come.

In a statement issued by the S.P.R.E.P. to date La Niña will differ in its impacts from country to country.

La Niña is expected to last right through to the first quarter of 2021, after which the La Niña in the Pacific region will gradually return to normal, though some parts of the Pacific may continue to experience the impacts. 

A simulated Pacific Islands Climate Outlook Forum (PICOF-7) will be hosted by S.P.R.E.P. through the Pacific Meteorological Council and its expert Pacific Islands Climate Services panel from the 22-23 October 2020.

This will provide more information on this event together with the Tropical Cyclone outlook for the 2020/21 season to the national meteorology services in the region.

Those in the central and eastern Pacific is expected to become more vulnerable to droughts, while countries in the south-west Pacific will become more prone to flooding and landslides, and tropical cyclones are more likely to form further west during this time.

Australia’s Bureau of Meteorology declared the arrival of La Niña to their mother shores after experiencing changes in both sea surface temperature as indicated by multiple climate monitoring systems.

Atmospheric pressure was also observed. 

In preparation for La Niña, national meteorological services across the Pacific have been well informed of the event by the Climate Oceans Support Programme in the Pacific Project and the Republic of Korea Pacific Island Climate Prediction Services (PI-CLIPS) Project. 

Low-lying coral atolls like Kiribati and Tuvalu are expected to be more concerned about La Niña as they have little supply of freshwater despite expecting less likely normal amount of rain.