Storms can profoundly affect the Great Lakes, sloshing water from one end of a lake’s basin to other, sometimes in a matter of hours, like displaced water in a bathtub. This lesson focuses on storm surges and seiches — Great Lakes water movements that can change lake levels dramatically during storms. Surges and seiches can arise suddenly and unexpectedly. While most are not dangerous, some have been deadly and are known to sweep people off piers and beaches, damage shorelines, sink ships, leave ships high and dry and cause flooding.
When Lake Michigan suddenly rose 10 feet and 150 feet past the normal water line on the beach on July 2, 1956, the rising water swept anglers off the pier and sent sunbathers running for safety as swimmers struggled against fierce currents. After the first surge of water, the lake receded 15 feet below the normal water line and then rolled back in a big wave. The seemingly haphazard temporary rise and fall of the lake’s water level could be explained: the people of Ludington had just come face-to-face with a Great Lakes seiche.
When a storm first moves over one of the lakes, typically the temperature drops and the wind changes direction. This disturbs the water in the lake and causes it to move in the same direction the storm is moving. For example, when a storm moves from west to east, water is moved from the western side to the eastern end of the lake. The water level in the eastern end of the lake is raised. This is called a storm surge. A surge can cause a difference in water level of several feet between both ends of the lake.
Storm surges may cause seiches. The word seiche is French for “to sway back and forth.” After a storm moves past the lake, and the wind and pressure are no longer pushing the water, the piled up water moves toward the opposite end of the lake. The water sloshes from one end of the lake to the other a few times until the water level is returned to normal. This sloshing back and forth is called a seiche. Often a seiche can be spotted because the water level will be high along the shore and within a relatively short period of time, the water level will then drop, sometimes leaving bottomlands exposed. Seiches may “slosh” back and forth like this several times before reaching equilibrium
Small-scale seiches and surges may not be noticed, but those that have significant water movement can Cause water levels to change by several feet in minutes. Cause anchored boats to bang together. Reach more than 10 feet, shocking those near the water. Take anywhere from 15 minutes to longer than 8 hours to slosh back and forth.
Here are a few of the bigger seiches on Lake Michigan. On July 4, 1929, over 45,000 people gathered in Grand Haven, at the Grand Haven State Park. A series of seiches attacked the Grand Haven shoreline after an early morning storm. The storm produced a seiche that generated into high winds and 20-foot waves. The seiche completely buried the Grand Haven pier sweeping people off and left helpless, while strong rip currents carried several more away from the beach. The deadly seiche of 1929 was responsible for taking ten lives. Nine years later, on July 13, 1938, another deadly seiche came about on the eastern shore of Lake Michigan at Holland, MI. It was a beautiful calm day on the beach at the Holland State Park. Later that day, a huge amount of water that was piled on the Wisconsin shore two days earlier due to an east wind, returned to Holland in the form of a seiche. The calm seas soon turned into monstrous ten-foot edge waves with fierce rip currents that swept people from the beach, pier and boats. The seiche of 1938 claimed five lives.
On June 26, 1954, the southern Lake Michigan experienced a seiche in numerous locations, including the entire Illinois shoreline. The seiche was caused by a squall line that started in Michigan City, IN. The seiche continued to build in size along the Illinois shore. Ten-foot waves struck North Avenue pier in downtown Chicago, IL. Fishermen were swept off the pier with many being rescued, however lives of eight people were lost. In both 1995 and 1998, a fierce derecho’s invaded the Great Lakes region both had the ingredients for a seiche.
Slim
YO INDY, did you make it up north??
Great read Slim. This is very interesting. Thanks.
Had to be pretty frightening to witness one of those and not know what’s going on. I’d love to see one, but from a distance of course. Like on top of one of the dunes. Good read Slim!
When I lived in Bay City there were several times when in the fall and spring when there was a strong SW wind that blew the water out of the Saginaw Bay and River and other times with a NE wind that blew the water into the bay and river but I do not recall a seiche
Slim
The current July mean here at Grand Rapids is 76.0 that is good for a departure of +3.5 and with just 7 days to go this month this should end up in the top warmest 15 July’s of record. The official overnight low at GRR looks to be 63. Here at my house the low was 62. At this time it is 66 here at my house the the last reading at GRR was 67.
Slim