Illinois State Water Survey - University of Illinois at Urbana-Champaign

Impacts of El Niño on Snowfall

Dr. Jim Angel, State Climatologist

Recent research at the Midwestern Climate Center has pointed to a significant reduction in total winter snowfall in the Midwest during the eight strong El Niño events in recent history (1957-58, 1965-66, 1972-73, 1982-83, 1986-87, 1987-1988, 1991-92, 1994-1995). These results are based on snowfall data from 3,690 sites in the United States.

The snowfall data averaged for these eight winters was compared to average snowfall data for the 38 other winters over the period of 1951-1952 to 1996-1997. The individual data points were used to develop grid-average values. The grid spacing is approximately 80 km on a side, so finer-scale features have been smoothed out.

• Annual Snowfall, Average of 8 El Nino Winters minus Average of All Other Winters during 1951-1997
• Annual Snowfall, Ratio of 8 El Nino Winters to All Other Winters during 1951-1997

Reductions on the order of 10 to 20 inches were found for:

• northern Illinois and Indiana
• along western Michigan and the upper peninsula of Michigan
• west central Minnesota, southeast North Dakota, and northeast South Dakota
• eastern edges of Lakes Erie and Ontario

The rest of the Midwest showed reductions on the order of 1 to 10 inches.