Meteorologists are almost certain that an El Niño winter is coming and that could mean a big change in what to expect in weather conditions.
Even in the Midwest.
According to the National Weather Service Climate Prediction Center, there is a “greater than 95% probability” that a El Niño continues through the northern hemisphere winter. The probability of a “strong” El Niño also increased from 66% last month to 71% this month.
According to the climate center’s ENSO blog, there is a 30% chance that the event will be on par with “some of the strongest El Niño since 1950.”
Last winter provided a surprising amount of rain and warmer-than-normal temperatures in the Chicago area and the latest forecast could mean a repeat, but meteorologists warn that “no two El Niño’s are the same.”
“A strong El Niño does not necessarily equate to strong local impacts, and the chances of related climate anomalies are typically lower than the chances of the El Niño itself,” the NWS reports.
What is El Niño?
El Niño refers to a time when sea surface temperatures in the Pacific Ocean, particularly near the equator, are unusually warm, according to Dr. Jim Angel, State Climatologist in Illinois. It is the opposite of La Niña.
“These (increases in water temperature) change weather patterns over the Pacific Ocean, which in turn changes weather patterns in much of the rest of the world,” Angel said.
According to the NWS, “under normal conditions in the Pacific Ocean, trade winds blow westward along the equator, carrying warm water from South America toward Asia.” However, thanks to a process called “upwelling,” cold water rises from the ocean floor to replace warm water. But El Niño causes the trade winds to weaken and warm water to be pushed eastward.
What effect does El Niño have on climatic conditions?
Typically, an El Niño year can mean parts of the northern US and Canada are drier and warmer than usual, but the Gulf Coast and Southeast can experience wetter than normal conditions, along with an increased risk of flooding.
What about the Chicago area?
Typically in Illinois, the impact of an El Niño event varies depending on its size, intensity and duration, Angel said.
“As a result, impacts may vary from event to event. Additionally, there may be other factors influencing Illinois weather during these events,” Angel said.
In general, some of the impacts could include:
- Summers tend to be a little cooler and wetter than average.
- Falls tend to be wetter and colder than average
- Winters tend to be warmer and drier.
- Springs tend to be drier than average
- Snowfall tends to be below average
- Heating degree days tend to be below average, which means lower heating bills.
Forecasts for next winter in the Chicago area suggest that residents could experience warmer than normal temperatures, with below normal precipitation.
During meteorological wintertaking place between December 1, 2023 and February 29, 2024, the CPC says its projections are “leaning upward” in terms of average temperatures in the Chicago area and throughout the upper Midwest .
Those same projections are “tilting downward” for the level of precipitation during that time.
Those projections currently it also lasts until March, according to NWS officials.
This evolution would be in line with the way in which El Niño phenomena usually develop. During those instances, Illinois and the Chicago area typically see warmer temperatures and below-normal precipitation, especially in the fall and winter months, according to researchers at the University of Illinois.