Precipitation

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Summary

  • Since 1951, total annual precipitation has increased by 14% in the U.S. Great Lakes region.
  • Total annual precipitation will likely continue to increase, but future projections precipitation vary, especially by season.
  • Lake effect snowfall is expected to increase until mid-century, afterward there is a projected transition to more winter rain.
  • The frequency of lake-effect precipitation may continue to increase in some areas.
  • Warming temperatures may cause snowfall to shift to more winter rain in the future.

 

Observed Changes in Precipitation

Changes have been observed in the frequency, amount, and type of precipitation falling in the Great Lakes region. Overall, total precipitation has increased by 14% since 1951 in the eight U.S. Great Lakes states, but trends vary by region. The Upper Peninsula of Michigan, northeastern Wisconsin, and parts of northern Minnesota have seen decreases, and the greatest increases have occurred in the southern Midwest. Changes in precipitation also vary by season. Changes in spring and summer precipitation have been highly variable across different parts of the Great Lakes region. Fall precipitation has increased more uniformly, and it is the only season in which the Upper Peninsula of Michigan has seen an increase. Winter precipitation has increased in the southern Midwest, roughly consistent with changes in the annual totals.

Since 1951, total annual precipitation has increased by 14% across the 8 U.S. Great Lakes states.

The percentage change in annual and seasonal precipitation from 1986-2015 compared to 1901-1960 (CONUS) and 1925-1960 (Alaska and Hawai’i). Image provided by the United States Global Change Research Program (USGCRP) Climate Science Special Report (CSSR, 2017).

Projected Changes in Precipitation

Overall, total annual precipitation is anticipated to continue to increase, though models vary widely on the magnitude and seasonal distribution of future changes.1 2 3 4 5 6 Most models project increases during the winter and spring seasons, but models are more varied when looking at the summer and fall. 7 8 9 10 11 One analysis indicates a potential 20-30 percent increase in winter and spring precipitation. 12 Winter and spring projections indicate the most notable increases of up to 30% on average. By contrast, summer and fall projections show little change to slight decreases on average, but individual models vary. Projections often diverge in the summer, with most models showing potential declines in total precipitation and the potential for more consecutive dry days, even as total annual precipitation is projected to increase. Other models project summer precipitation increases in the future. Practitioners may want to consider multiple summertime scenarios to explore uncertainty related to future precipitation events.

The projected changes in seasonal precipitation for 2070-2099 (compared to 1976-2005) assuming high greenhouse gas emissions (RCP 8.5 scenario). Image provide by the United States Global Change Research Program (USGCRP) Climate Science Special Report (CSSR, 2017).

Snowfall, Snow Cover, and Snow Depth

Snowfall has increased in northern lake-effect zones in the Great Lakes basin, while snowfall totals in Illinois, Indiana, and Ohio have declined with rising temperatures. 1 Warmer Great Lakes surface water temperatures and declining Great Lakes ice cover have likely driven the observed increases in lake-effect snow. As regional temperatures continue to rise and further warm the Great Lakes, areas in lake-effect zones may continue to see increasing lake-effect snowfall. Areas in more southern lake-effect zones may see lake-effect snow replaced by lake-effect rain, as warming regional temperatures result in less favorable conditions for precipitation to reach the surface as snow. 1   1   1

Snow cover and snow depth outside the lake-effect zone of the Great Lakes region are expected to continue to decrease, having already experienced some of the greatest declines of any region in North America. 1 Between 1975 and 2004, the number of days with snow on the ground decreased by five days per decade. The average snow depth across the region also decreased by 3 inches (5.1 cm) over the same time period. 1

Read more about observed and projected changes to snow in the Great Lakes region »

Observed geographic changes in snowfall from 1961-1990 to 1981-2010. Image provided by the Midwestern Regional Climate Center (MRCC).

Extreme Precipitation

Extreme precipitation events have become more intense and more frequent. Across the eight states in the Great Lakes region, the amount of precipitation falling in the heaviest 1% of precipitation days increased by 35% from 1951 to 2017. 13

The observed trends of greater frequency and intensity of extreme storm events are projected to continue or accelerate as the effects of climate change become more pronounced. 14 15 16 17 18 Though the frequency of severe storms such as thunderstorms, heavy rains, and snow may increase, the occurrence of other severe weather events such as hailstorms, tornadoes, and ice storms is too uncertain to project. Planners should anticipate these types of storms to continue, and monitor the research to understand changes in their behavior. 19 20

Read more about changes in extreme precipitation»

The observed changes in heavy precipitation from 1901 through 2016. Image provided by the United States Global Change Research Program (USGCRP) Climate Science Special Report (CSSR, 2017).

References

  1. Walsh, J., and Coauthors, 2014: Climate Change Impacts in the United States: The Third National Climate Assessment. J. M. Melillo, T. C. Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program.
  2. Pryor, S. C., D. Scavia, C. Downer, M. Gaden, L. Iverson, R. Nordstrom, J. Patz, and G. P. Robertson, 2014: Chapter 18: Midwest. Climate Change Impacts in the United States: The Third National Climate Assessment, J. M. Melillo, T. C. Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program, 418-440. 10.7930/J0J1012N.
  3. Barlage, M. J., P. L. Richards, P. J. Sousounis, and A. J. Brenner, 2002: Impacts of climate change and land-use change on runoff from a Great Lakes watershed. Journal of Great Lakes Research, 28, 568-582.
  4. Grover, E. K., and P. J. Sousounis, 2002: The Influence of Large-Scale Flow on Fall Precipitation Systems in the Great Lakes Basin. Journal of Climate, 15, 1943.
  5. McBean, E., 2008: Assessment of impact of climate change on water resources: a long-term analysis of the Great Lakes of North America. Hydrology and Earth System Sciences, 12, 239.
  6. Wuebbles, D. J., and K. Hayhoe, 2004: Climate Change Projections for the United States Midwest – Climate Change and Environmental Policy. Mitigation and Adaptation Strategies for Global Change, 9, 335-363.
  7. Walsh, J., and Coauthors, 2014: Climate Change Impacts in the United States: The Third National Climate Assessment. J. M. Melillo, T. C. Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program.
  8. Argyilan, E., and S. L. Forman, 2003: Lake Level Response to Seasonal Climatic Variability in the Lake Michigan–Huron System from 1920 to 1995. Journal of Great Lakes Research, 29, 488–500.
  9. Hayhoe, K., J. VanDorn, T. Croley, N. Schlegal, and D. Wuebbles, 2010: Regional climate change projections for Chicago and the US Great Lakes. Journal of Great Lakes Research, 36, 7-21.
  10. Schwab, D. J., S. A. Green, H. A. Vanderploeg, J. B. Cotner, B. A. Biddanda, W. C. Kerfoot, and J. W. Budd, 2008: Doughnut in the desert: Late-winter production pulse in southern Lake Michigan. Limnology and Oceanography, 53, 589.
  11. Weubbles, D. J., 2006: Executive Summary Updated 2005: Confronting Climate Change in the Great Lakes Region. Union of Concerned Scientists.
  12. Hayhoe, K., J. VanDorn, T. Croley, N. Schlegal, and D. Wuebbles, 2010: Regional climate change projections for Chicago and the US Great Lakes. Journal of Great Lakes Research, 36, 7-21.
  13. GLISA. Climate Trends in the Great Lakes Region. http://glisa.umich.edu/media/files/GLISA%202%20Pager%202019.pdf
  14. Changnon, S. A., 2009: Temporal and spatial distributions of wind storm damages in the United States. Climatic Change, 94, 473.
  15. Changnon, S. A., 2011: Temporal distribution of weather catastrophes in the USA. Climatic Change, 106, 129.
  16. Changnon, S. A., and N. E. Westcott, 2002: Heavy rainstorms in Chicago: increasing frequency, altered impacts and future implications. Journal of the American Water Resources Association, 38, 1467–1475.
  17. Hejazi, M., 2009: Impacts of Urbanization and Climate Variability on Floods in Northeastern Illinois. Journal of Hydrologic Engineering, 14, 606.
  18. Vavrus, S., and J. Van Dorn, 2010: Projected future temperature and precipitation extremes in Chicago. Journal of Great Lakes Research, 36, 22-32.
  19. Changnon, D., and R. Bigley, 2005: Fluctuations in US Freezing Rain Days. Climatic Change, 69, 229.
  20. Changnon, S. A., and K. E. Kunkel, 2006: Severe Storms in the Midwest. Illinois State Water Survey Informational/Educational Material 2006-06, Champaign, IL, 74.