El Niño has officially formed

“The declaration of the El Niño advisory is just the beginning as scientists will continue to unpack information as it comes,” DiLiberto said.

The El Niño event is weak as of now but, by peak winter, there is a 56% chance it becomes strong. While that sounds like a coin toss, and it nearly is, DiLiberto said that number is fairly high. There are not that many El Niño events reaching that strength since 1950, DiLiberto said.

That all means, if it rings true, the county could be in for another wet winter.

The phenomena of both El Niño and La Niña weather patterns date back hundreds of years to Peruvian fishers who noticed a change in the water temperature and humidity in the air. It had a direct correlation on the abundance of anchovies they would catch. In Spanish, El Niño translates to little boy, meaning baby Jesus, because the weather phenomenon generally happens around Christmas. The warm surface water affects fish that eat phytoplankton. The warmer waters can also bring tropical species, like yellowtail and albacore tuna, into areas that are normally too cold, like Southeast Asia, according to the NOAA.

During an El Niño weather pattern, trade winds tend to weaken and warmer surface water pushes toward South America fueling an intensification and shift on the jet stream. The warm water triggers the thunderstorms in the middle of the ocean to activate, which means a wetter and stormier winter for the county.

Think of the jet stream like a fire hose, DiLiberto said, a person standing under a fire hose will be soaked, and the same goes for the jet stream, which could be influenced by El Niño and it ultimately will determine the amount of rain the county will see over winter.

“The stronger the El Niño event means it will have more of an influence on the weather system than if it’s weaker, and that’s because many factors go into the weather system,” DiLiberto said.

To declare an El Niño event, there are multiple factors, sea surface temperatures along the equatorial Pacific Ocean, trade wind patterns and climate models predicting those numbers will be sustainable over time.

NOAA tracks the surface temperature along the equatorial Pacific Ocean. When temperatures are more than .5 degrees Celsius warmer than the long-term average, which is data tracked from 1991 to 2020, it’s one of three factors that indicate El Niño is likely to occur. Results from data showed the sea surface temperatures in the tropical Pacific Ocean in May were .5 degrees Celsius above the long-term average. And just last week, the agency recorded temperatures .8 degrees Celsius above the long-term average. May wasn’t a blip and the temperatures have been rising since then, DiLiberto said.

The second factor is the expectation the ocean temperature will last for five consecutive seasons. NOAA computes seasons in three month groupings, he added. And its climate models predict those numbers to be easily reached over that time frame. The last factor is when there is increased precipitation in the Pacific and a weakening of the trade winds, which both have occurred, he added.

El Niño last came in 2018 but it was weak. El Niño typically lasts around nine months but can last up to two years, in some instances. On average, it occurs once every seven years and is generally followed by a La Niña event the following year, Warren Blier, National Weather Service science officer, said.