Weather bureau says La Niña will bring heavy rains

The Vanuatu Meteorology and Geo-Hazards Department warns there could be flooding and landslides in some areas in Vanuatu as La Niña climate conditions approach.

The Acting Director of the department, Allan Rarai, says with the La Niña and the rainy season starting to develop, Vanuatu will receive heavier rainfall from the month of September to around March next year.

Mr Rarai says Vanuatu will experience the full impact of La Niña in October.

“With the rainfall that we will get, there could be flooding and landslides on the islands of Vanuatu,” Mr Rarai said.

“And that has happened in some places like in Maewo and other places that have experienced flooding in the past.”

He says the department has released its first advisory on La Niña’s weather patterns this week.

The advisory stated that the El Niño-Southern Oscillation (ENSO) outlook remains at a La Niña alert level.

This means the chance of La Niña forming in 2020 is around 70 per cent. Continued cooling of the tropical Pacific Ocean and recent changes in tropical weather patterns suggest La Niña could become established in Spring (September to November) 2020.

Most climate models indicate the La Niña threshold could be reached by October, and is likely to persist into December 2020.

Mr Rarai says, “As we speak, La Niña is at 70 per cent and hasn’t fully developed yet but there are high chances for it to fully develop and once it is fully developed we will expect more rain.

“We are also expecting more rain around February 2021.”

Vanuatu’s rainy season is from the month of December to March while its dry season annually is from the month of August to September.

However, Vanuatu has begun experiencing rain in September which the Vanuatu Meteorology and Geo-Hazards Department says is linked to the development of La Niña.

La Niña and El Niño are ocean-atmosphere phenomena that are opposite phases of the ENSO cycle, which is a scientific term that describes the fluctuations in temperature between the ocean and atmosphere in the tropical Eastern Central Pacific Ocean.

La Niña, which is a Spanish term for ‘little girl’ involves ‘cooling of the sea surface’, while El Niño or ‘little boy’ involves the ‘warming of the sea surface’.

These changes from normal sea surface temperatures can have large-scale impacts on ocean processes and global weather and climate. During a period of La Niña, the sea surface temperature can be lower than normal by 3 to 5 °C.

El Niño and La Niña episodes usually last nine to 12 months, but some prolonged events may last for years. While their frequency can be quite irregular, El Niño and La Niña events occur on average every two to seven years.

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