拉尼娜天气预计将持续到2021年

The United Nations weather agency says a continuing weather event places some countries at risk of weather-related problems.

The World Meteorological Organization, or WMO, predicts La Ni?a will continue to affect the world's weather through January. The weather event is expected to bring drier and wetter conditions than normal to different parts of the world.

La Ni?a is a weather pattern that happens in the Pacific Ocean but affects weather around the world. A La Ni?a event happens when ocean surface waters cool along the Pacific coast of the South American tropics. This takes place about every two to seven years.

The latest predictions show La Ni?a will cause drier than normal conditions in much of East Africa and lead to more rainfall in southern Africa. Central Asia is likely to see below normal rainfall earlier than usual.

The WMO reports some of the Pacific islands and the northern part of South America will see unusual changes in wet weather. These changes in weather patterns can put countries in some parts of the world at greater risk.

Gavin Iley is a humanitarian expert for the WMO. He told VOA parts of eastern Africa were of special concern. The area is already suffering such problems as locust insects eating crops. Weather imaging suggests below normal rainfall for a large part of eastern Africa, Iley explained. So that could have a number of effects on places like Somalia.

The WMO said governments can use weather predictions to plan ways to reduce harmful effects on agriculture, health, water resources and disaster supervision. All of these are sensitive to a changing climate.

Maxx Dilley is a director of climate services at the WMO. He said governments can use predictions of La Ni?a to adapt their action plans.

"You can imagine in the agricultural sector that some crops will do well under wet conditions and others will do better under dry conditions," Dilley said. And there are agricultural supervision methods that can be changed based on whether dry or wet weather is expected.

Dilley said the WMO is trying harder to make its predictions with attention to specific concerns. These include issues like food security or human health.

Dilley gave one example related to health and disease. He said wet conditions alone do not lead to more cases of dengue fever or malaria. Dilley explained that temperature, wet air and vegetation create the conditions for mosquito populations to rise.

So, rather than just giving a rainfall prediction, he said, meteorologists will provide disease predictions. The goal is to use the predictions to control dengue fever or malaria.

I'm Alice Bryant.

Lisa Schlein reported this story for VOA News. Alice Bryant adapted it for Learning English. Mario Ritter, Jr. was the editor.