Upwind Lakes Can Influence the Intensity of Lake-Effect Snowstorms over Downwind Lakes, Illinois State Water Survey

ISWS Press Release

For Immediate Release April 11, 2013
Upwind Lakes Can Influence the Intensity of Lake-Effect Snowstorms over Downwind Lakes
David Kristovich - (217) 333-7399, dkristo@illinois.edu
Lisa Sheppard - (217) 244-7270, sheppard@illinois.edu

CHAMPAIGN, Ill. - Research shows that small lakes even hundreds of miles away can cause lake-effect snows to intensify around the Great Lakes, a phenomenon that may occur more often with climate change, according to David Kristovich, head of the Center for Atmospheric Science at the Illinois State Water Survey, University of Illinois.

When small lakes freeze in the winter, they have little influence over air masses passing by.  Yet global warming has been decreasing the amount of time that lakes in North America are ice covered.

Lake-effect snow develops when frigid air blows over warmer lakes. The sudden burst of heat under the cold air causes upward motions, causing moisture from the lakes to condense into clouds. Some fraction of that moisture eventually falls back to the surface as snow.

Sears Tower, Chicago, IL

These types of storms can be very intense, with the potential for dropping several feet of snow. Weather radar has even shown mini-cyclones dropping several inches of snow per hour in small, localized areas.

“This is a particular concern in the northern U.S. and in Canada where small lakes are plentiful, with the potential to affect larger lakes,” Kristovich said.  “Unfrozen lakes can produce heavy snow in the area as well as in heavily populated communities surrounding the Great Lakes.  With climate change, this may happen more and more.”

Kristovich's research also shows that modification of the air by some of the Great Lakes can affect lake-effect snow over other lakes.  Michigan and Huron Lakes, which are upwind of Lakes Erie and Ontario when cold wind blows, distribute heat and moisture into the air, increasing the intensity of snowstorms downwind.  In addition, the atmospheric circulations generated by one lake expand over the second lake, producing more snow.

 “Recently, we studied cloud and snow bands that stretch across more than one of the Great Lakes,” Kristovich said. “The intensity of the lake-effect snow increased as the air moved from one lake to the next.”

Kristovich is set to begin a National Science Foundation-funded research project in which aircraft will fly over Lake Ontario chasing air bands across the lake and collecting data intended to vastly improve computer models that predict lake-effect snowstorms.

Equations used to describe physical processes in the weather models are only as good as the data available.  New data will benefit community residents who live near the Great Lakes with advanced predictions on where snow will fly and how much snow will fall.


The Illinois State Water Survey at the University of Illinois at Urbana-Champaign, a division of the Prairie Research Institute, is the primary agency in Illinois concerned with water and atmospheric resources.

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