Strong Chance El Nino Will Form in Pacific in 2019

Global forecasters see a 75 to 80 percent chance that an El Nino could form within the next three months, possibly bringing heavy rainfall and flooding to some parts of the United States.

The World Meteorological Organization said on Tuesday that there is a strong chance of an El Nino forming by February. However, it is likely the event will be relatively weak.

El Nino is a naturally occurring weather event that warms the ocean surface, raising sea surface temperatures to above average in the central and eastern tropical Pacific Ocean. It is often associated with dry winter conditions in southeastern Africa and northern Brazil and wetter conditions along the Gulf Coast of the U.S.

The change in temperature brings increased rain over the tropical Pacific Ocean while rain over Indonesia tends to decrease. Additionally, the easterly low-level surface winds either weaken or blow in the opposite direction.

Although sea surface temperatures are already at weak El Nino levels in parts of the tropical Pacific, the necessary atmospheric conditions for the weather event "have not yet materialized." However, model forecasts suggest these conditions will appear within the next two months, with a 75 to 80 percent chance of "full-fledged" El Nino developing between December and February.

Additionally, forecasters see about a 60 percent chance the El Nino will continue through April.

The WMO predicts El Nino could range from a warm-neutral condition to a moderate strength event. Despite its strength, it will not reach the levels of the 2015-2016 event that caused droughts, flooding and coral bleaching in parts of the world. The 2017-2018 event is expected to raise sea surface temperatures to 0.8 to 1.2 degrees Celsius above average.

Forecast models predicts above-normal surface air temperatures will occur in parts of Asia, Europe, North America, the Caribbean, Africa, Australia, Indonesia and South America. A high probability also exists that below-normal rainfall will occur in the Caribbean; islands off the coast of Southeast Asia; Central America; parts of northern, coastal and southern South America; the southern Indonesian archipelago and southern Africa.

Above-normal rainfall is expected in parts of southern and northwest North America; southeast South America; central, northern and southwest Asia and parts of Europe.

Even if El Nino does not reach the levels of three years ago, Maxx Dilley, director of the World Meteorological Organization's Climate Prediction and Adaptation Branch, said the event "can still significantly affect rainfall and temperature patterns in many regions, with important consequences to agricultural and food security sectors, and for management of water resources and public health."

It may also "combine with long-term climate change to boost 2019 global temperatures."

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