NOAA’s Climate Prediction Center has released its latest winter weather forecast, but how will El Niño affect things in the Chicago area?
In general, El Nino leads to warmer than average temperatures and drier than normal precipitation conditions in the Midwest. NOAA believes that pattern will last until 2024.
According to NOAA’s Seasonal Temperature Outlook, forecasters are “leaning” toward a warmer-than-normal winter for most of Illinois and Indiana from Dec. 1, 2023, to Feb. 29, 2024.
That level of confidence grows in areas near Lake Michigan, where forecasters say temperatures are “likely” above normal during the winter months, including in the city of Chicago.
Most of the Midwest and much of the northern United States will see above-average temperatures, according to forecasts released Thursday.
In terms of precipitation, most of Illinois is expected to have normal snowfall this winter, but nearly all of Indiana and far eastern Illinois will have below-average winter precipitation.
Consistent with previous El Niño events, the southern United States is expected to see wetter-than-normal conditions.
What is El Nino?
El Niño refers to a period of unusually warm sea surface temperatures in the Pacific Ocean, particularly near the equator. Dr. Jim Angel, a state climatologist In Illinois. It is the opposite of La Nina.
“These (increased water temperatures) are changing the weather patterns of the Pacific Ocean, which are changing the weather patterns of the rest of the world,” Angell said.
According to the NWS, “Under normal conditions in the Pacific Ocean, trade winds blow westward across the equator, carrying warm water from South America toward Asia.” Thanks to a process called “upwelling,” however, cold water instead of warm water rises from the ocean floor. But due to El Niño, trade winds weaken and warm water is pushed eastward.
What does El Niño do to the weather?
In general, an El Niño year means that parts of the northern United States and Canada will be drier and warmer than usual, but the Gulf Coast and Southeast will see wetter-than-normal conditions, and increased flood risk.
What about the Chicago area?
The Chicago area had a surprising amount of rain and warmer temperatures than normal last winter, and the latest forecast means a repeat could happen.
For Illinois in general, the impact of an El Niño event varies depending on its size, intensity and duration, Angell said.
“As a result, the impacts will vary from one event to the next. Additionally, there may be other factors affecting Illinois weather during these events,” Angell said.
Commonly, some of the impacts include:
- Summers are slightly cooler and wetter than average
- The falls are wetter and colder than average
- Winters are hot and dry
- Springs are drier than average
- Snowfall will be below average
- Heating degree days are below average, which means lower heating bills.
Such development is consistent with how El Niño events typically unfold. During those events, parts of Illinois and Chicago typically see warmer temperatures and less precipitation than normal, especially during the fall and winter months, according to University of Illinois researchers.