As a La Niña watch issued, here's how the pattern could impact Illinois' weather

The National Weather Service’s Climate Prediction Center has issued a La Niña watch for later this year, as the ongoing El Niño pattern shows signs of weakening.

That El Niño pattern may have hit its peak in January, with its impacts slowly beginning to fade, according to forecasters.

According to an alert issued Thursday, forecasters believe that there is a 79% chance that the world will transition from the El Niño pattern, which has had a significant impact on weather conditions in the United States and across the globe, to a more neutral pattern during the spring months.

There is also a growing chance, roughly 55%, that the world will move quickly into a La Niña pattern between June and August, according to the watch issued Thursday.

So what does all of that mean?

According to the University of Illinois, La Niña patterns occur when sea-surface temperatures along the equator in the Pacific Ocean are unusually cold, compared to the unusually warm sea-surface temperatures that occur during an El Niño pattern.

Trade winds grow in strength during those events according to the NOAA, pushing warmer water toward Asia, which then allows cold water to rise to the surface near the west coast of the Americas.

As a result of the cooler waters in the ocean, the jet stream then pushes northward, funneling heavy rain toward the west coast, but ultimately causing drought conditions in the southwest and southern United States.  

In terms of impacts on Illinois, researchers say that summers tend to be warmer and drier than normal during a La Niña pattern, while fall tends to see cooler and wetter conditions.

Winters tend to be warmer during La Niña events, but Illinois is more prone to cold snaps and heavy snow events, according to researchers.  

Elsewhere, La Niña can also cause extensive droughts in the western U.S., and can lead to more hurricanes in the Atlantic Ocean as well, according to PBS.