El Nino and La Nina are large-scale global weather patterns that result from changes in ocean temperatures in the equatorial Pacific Ocean region.
El Nino is caused when the temperatures are warmer than normal. La Nina is when they're cooler than normal.
Some scientists believe we're coming out of our El Nino event and heading for a La Nina event this upcoming winter. In the Pacific Northwest, La Ninas tend to mean cooler and wetter than normal winters, but it's not a guarantee. Still, Seattle has averaged 20 inches of snow in La Nina years, compared to 10 inches in normal years.
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