El Niño occurs when sea surface temperatures in the Pacific Ocean become extremely warm, and have higher than normal pressure between the warm water and cooler water in the ocean.
Warmer ocean water means it will be slightly warmer than normal for this time of year, as well.
In El Niño years, there is a period of below-average rainfall for part of the world, although the overall pattern will remain the same.
In La Niña years, below-average rainfall for part of the world, but higher rainfall, also as expected, for all of the region.
Both El Niño and La Niña’s affect weather, although La Niña is known to be more powerful. For example, in 2015, the impacts of La Niña were short-lived.
What is the difference between La Niña and El Niño?
The average sea surface temperature in the western equatorial Pacific is extremely close to average this time of year, making it difficult to tell if it is “La Niña,” or the cooling phase, or “El Niño,” which last for longer and can last years. But when El Niño occurs, the sea surface temperatures are above average and sometimes well above average.
During El Niño, the winds that blow off the coast of North America are more often westerly, as opposed to the west, and the sea surface temperatures near the equator are above average.
The frequency of El Niño and La Niña is very, very short-lived.
While the climate phenomenon lasts for years, the frequency of El Niño and La Niña is very, very short-lived.
According to climate scientists, El Niño usually happens every two to seven years. The last El Niño happened in 2014. The latest La Niña occurred in 2014 and 2015. The odds of having an El Niño from now until next year are 21 times out of 100.
Does El Niño or La Niña actually change the weather?
Yes. They create huge storms, and also have a wider swath of rain, flooding and dust storms.
Each season changes its type and intensity. In this summer and fall of 2018, La Niña developed in the Pacific Ocean, possibly causing some drought in the south as well as coastal smog.
In both El Niño and La Niña years, hot storms (think tornadoes) develop in the North Atlantic, but also can occur in the North Atlantic during a strong El Niño. The lines of storms along the coastline are called El Niño/La Niña waves, so it’s not clear which is which, since the cold air from one would blow toward the other.
What can I do to prepare for El Niño or La Niña?
The question “What can I do to prepare for El Niño or La Niña?” brings with it many myths. I’ll debunk three of them right here.
1. Don’t be afraid to get the water running.
Wrong. If you have a pool or pond, make sure to drain it, so the cold air does not mix with the warm water and create a flushing effect. You also should not submerge your pool.
2. Don’t be afraid to get the lettuce out of the containers.
Wrong. It may be a little messy, but it is safer than having the water stagnate at normal levels. I will discuss how to get lettuce to reach decent quality after draining it, but remember — if you only put it into the container once, it is unlikely to develop good flavour.
3. Don’t get out the lanterns and candles.
Wrong. Lighting a candle won’t help you during an El Niño. Remember to also turn off the heat.
“Hold the water” is a different story altogether. As in: Don’t be afraid to get out there.
More information about El Niño can be found on NOAA’s El Niño page.
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