What is an El Niño, and what effects will this climate pattern have on spring weather?
Despite their simple names, these weather systems can cause a whole lot of trouble.
It's official: El Niño is back.
On Thursday, scientists at the Climate Prediction Center confirmed the climate pattern formed in the Pacific this week.
The center said "weak El Niño conditions are present" and would likely last through the spring.
The climate pattern plays a big role in what weather we can expect across the United States and around the world. And it's possible El Niños might get stronger. A study released in December claims future El Niños will grow more powerful and lead to more extreme weather because of global warming.
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So, what is El Niño, and what kind of forecasts can we anticipate? Here's what you need to know:
What is El Niño?
It's a natural climate pattern where sea water in the central and eastern tropical Pacific Ocean is warmer than average.
As for its name, El Niño means the Little Boy, or Christ Child in Spanish. El Niño was originally recognized by fishermen off the coast of South America in the 1600s, with the appearance of unusually warm water in the Pacific Ocean around Christmas.
According to the National Oceanic and Atmospheric Administration, scientists today measure El Niño by calculating the average sea-surface temperature each month, then averaging it with the previous and following months.
That number is compared to average temperatures for the same three-month period between 1986 and 2015, called the Oceanic Niño index.
When the index hits 0.5 degrees Celsius warmer or more, it's classified as an El Niño. When it's 0.5 degrees Celsius cooler or more, it's a La Niña.
The overall climate pattern is known as the El Niño-Southern Oscillation (ENSO) cycle.
How does it affect our weather?
During an El Niño, the southern part of the U.S. typically experiences wetter than average conditions, while the northern part is less stormy and milder than usual, said NOAA. During a La Niña, it flips, with colder and stormier conditions to the north and warmer, less stormy conditions across the south.
What should we expect this year?
Because this El Niño is at such a weak strength, forecasters believe the climate pattern won't have a significant impact on our weather. However, forecasts for the next few weeks are for soggy conditions across the southern U.S., which is common with El Nino.
NOAA doesn't predict how El Niño will impact the spring severe storm season. However, research released in 2016 showed a weak El Niño could increase the risk of tornado outbreaks in May in the upper Midwest.
El Niño also tends to suppress the number of hurricanes that form in the Atlantic, which NOAA does factor in when issuing its seasonal hurricane predictions in May.