Answered by Mike Huston, Meteorologist, National Weather Service
Unusually warm sea surface temperatures across the tropical Pacific continue to support El Niño conditions and forecasters at the Climate Prediction Center unanimously favor the development of a “strong” El Niño which is expected to persist through the winter and gradually weaken during the spring of 2016. Across the United States, temperature and precipitation impacts associated with El Niño are expected to remain minimal during the early fall months before increasing through the winter contributing to a shift in the probabilities toward a warmer and drier winter for southeast Idaho. (Figure 1)
The presence of El Niño can significantly influence weather patterns across a large portion of the globe for an extended period of time. The strength of an El Niño can also influence the likelihood that the impacts shown above will occur. During strong El Niño events (Figure 2), the Pacific storm track normally shifts south into the southern tier states while the Polar storm track dips southeast across eastern Canada leaving the Pacific Northwest drier than normal with a large region of above normal temperatures stretching across the northern tier states. To be continued next week
An El Niño is a temporary change in the climate of the Pacific ocean, in the region around the equator. During an El Niño year, the winds that usually blow sun-warmed Pacific air and water from east to west stop blowing altogether, or in some cases even start blowing in the opposite direction. Warm water starts to pool in the eastern waters off South America, instead of the western areas of the Pacific near Indonesia and Australia, triggering a variety of wild weather patterns
throughout the world.
How does ocean’s water temperature affect the weather? The following experiment will help us to understand.
Materials: Two paper cups, hot water, cold water,plastic wrap, rubber band
- 1. Fill one cup with hot water.
- Fill the other cup with cold water.
- Place your hand over each cup. Don’t touch the water, but feel the air. Does the temperature of the water affect the temperature of the air above the cups?
- Use a rubber band to secure plastic wrap over the hot water cup. Do you see water drops? How do your findings apply to El Niño? The moisture in the air over the cup with warm water collects on the inside of the plastic wrap, and, as the air cools, forms tiny droplets and falls back down. You created rain!
Imagine the air over the warm water of the tropical Pacific Ocean. Huge amounts of water evaporate into the air. Once the warm wet air starts to cool, rain clouds form and wetter conditions result in parts of North and South American countries.