Strengthening El Niño could continue into spring, new forecast says

The National Weather Service says an ongoing El Niño pattern has continued to strengthen and could persist into next spring.

According to the latest guidance from the Climate Prediction Center, there remains a greater than 80% chance of a “strong-to-very strong” El Niño persisting in the Northern Hemisphere until at least the spring, which could have some significant impacts on weather in the Chicago area.

That guidance cited data showing an ongoing El Niño pattern which has further strengthened over the last month, with sea surface temperatures more than four degrees Celsius above normal across the eastern Pacific Ocean.

As that strengthening continues, it remains highly likely the ongoing El Niño pattern will exceed all previously recorded events dating back to the mid-20^th century.

So what could that pattern lead to in the Chicago area?

According to the National Weather Service, an El Niño weather pattern occurs when the trade winds in the Pacific Ocean weaken, allowing warmer ocean water to be pushed to the east and toward the west coast of the Americas. That pattern has been firmly established this year, with sea surface temperatures soaring in the Pacific Ocean near the coast of the Americas.

Those warmer waters then push the Pacific jet stream further to the south, which can allow warm, dry air to flood over the northern United States and can cause cooler and wetter conditions across the southern U.S.

As for the impacts on Illinois, researchers at the Illinois State Climatologist’s Office caution that not all El Niño patterns have noticeable impacts. In this situation however, given the strong nature of the El Niño pattern, it is more likely that those patterns could change the weather in Illinois, especially in the winter.

According to the University of Illinois, winters during El Niño years tend to be warmer and drier, with below-average snowfall typically occurring in those years.

What’s more, springs during El Niño patterns tend to be drier on average, which could impact the start of the growing season in the Midwest.

The Climate Prediction Center’s seasonal temperature outlook, issued in September, appears to validate that pattern potentially emerging in the Chicago area, with the forecast leaning toward above-average temperatures during meteorological fall and into the month of December.

from NBC Chicago https://ift.tt/NcmdoZ9