In October of 2023 The Climate Prediction Center (CPC) said that conditions were indicative of an ongoing ‘Strong’ El Niño.

El Niño Years

During a year when El Niño is present, the United States typically begins to see significant impacts in the late fall and early winter. El Niño events are associated with above average temperatures in the Great Lakes region, and below average winter precipitation in the Lake Erie and southern Lake Michigan-Huron basins.

Above average temperatures in winter in the Great Lakes region will generally result in lower snowpack, higher lake surface temperatures, and lower ice coverage. These all have an impact on the Net Basin Supply (NBS), which consists of evaporation that takes water from the lakes, and precipitation and runoff that add water to the lakes. NBS is the main impetus for Great Lakes static water level changes. Previous El Niño years were 1958, 1983, and 1998.

The 1958 El Niño is categorized as a ‘Strong’ El Niño, while the 1983 and 1998 El Niño events were classified as ‘Very Strong’. The 1958, 1983, and 1998 water level scenarios are represented by the green, blue, and pink lines, respectively. Also, the gray shaded area on the plot represents the full range of possible outcomes using historical sequences of NBS from 1900 through 2022. 

el nino historical cycles - army corp of engineers 2024Summary and Outlook

The purple plume that represents Great Lakes water levels in the 12 months during and after the 8 strongest El Niño events is shifted toward the bottom of the full range of possible outcomes (gray shaded area) for water levels on all the lakes. 

Hydrometeorological conditions like those in 1983 (blue line) showed a more typical seasonal cycle and would result in water levels being above average water levels on all lakes by the end of the 12 months. The 1958 scenario (green line) was indicative of drier conditions across the lakes and all lakes would finish the 12-month period below average, except Lake Ontario. The 1998 scenario (pink line) experienced variable conditions throughout the year, but all lakes would end the 12 months with water levels below average. 

The current seasonal temperature forecasts for the winter and early spring (January, February, March) shows a likelihood of above normal temperatures across the Great Lakes. The current seasonal precipitation forecast shows a likelihood toward below average precipitation across most of the Great Lakes basin.  

2024 seasonal temp precip outlook


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