At North Avenue Beach at water's edge around 6 p.m. Wednesday, things were calm.
A seiche can be serious business. It's like a bathtub effect. There is downdraft on the lake, so the lake at St. Joe, Michigan dropped by two feet. Given the bathtub effect, the water has to go somewhere and the National Weather Service issued its warning earlier Wednesday afternoon.
At 4 p.m., the park district put up the red flags and told the swimmers to get out of the water. The Office of Emergency Management and Communication notified all of the city departments. There's a precautionary note for Navy Pier, life goes on as usual but the suggestion is, if you're there don't get too close to the water, it's not a good idea because at some point the water level is going to come up.
It's unknown exactly when and don't know exactly by how much, but just to be on the safe side it's not something to be toyed with.
Back in 1954, there was a 10-foot seiche that hit Chicago fairly rapidly and knocked about eight fishermen off of a dock. They lost their lives.
"You don't want to be wading out there and have a 24-inch rise knock you off balance, as well as the folks on Navy Pier, as well as out there in the marina," said Jim Argiropoulos, OEMC.
Severe weather did sweep through the Chicago area Wednesday evening.
High winds knocked down trees, including one along Bateman Road in Barrington Hills. The storm brought hail to Algonquin and downpours to many areas.