If you’ve seen a weather forecast in the past few weeks, you know that weather has been a bit extreme. Just a few days ago, a massive cold front pushed through the Eastern USA causing tornadoes in the Southeast and blizzards in the Northeast. Throughout all of it, you keep hearing the phrase “El Niño ” being tossed about. Most people pretend they know what this means- or maybe that is just me? I’ve done some intense Google searching within the past five minutes and am now fully prepared to answer the question, “What the heck is El Niño?”
According to the National Oceanic and Atmospheric Administration (NOAA), there is a naturally- occurring weather cycle called the El Niño-Southern Oscillation (ENSO) cycle. This cycle is centered in the tropical eastern Pacific Ocean from the International Date Line to 120 degrees longitude. (Translation: that big section of ocean south of Hawaii and west of South America.) During this cycle, the temperature of the ocean fluctuates. When it is warmer than normal, we have El Niño. When it is cooler than normal, we have La Niña.
During the El Niño portion of the cycle, the jet stream changes so that western and central North America are warmer and drier while eastern and southern areas are cooler and wetter. La Niña brings the exact opposite. Each portion of the cycle typically last from 9-12 months with a complete cycle happening every 2-7 years.
Here are some neat-o maps from NOAA that shows how global weather changes during these phases.
Typical El Niño Effects: December Through February
Typical El Niño Effects: June Through August
Typical La Niña Effects: December Through February
Typical La Niña Effects: June Through August