Waterspouts are possible in Lake Michigan Wednesday, including potentially in the Chicago area, forecasters warn.
The National Weather Service in Chicago postponed its weekly radio test Wednesday morning "due to thunderstorm and waterspout potential in our Lake Michigan coverage area," the agency said.
The test was rescheduled for between 11 a.m. and noon Thursday.
In the Milwaukee area, the National Weather Service warned residents to "be on the lookout for waterspouts" with scattered showers and storms possible.
Images showed what appeared to be a waterspout in Shorewood, Wisconsin, just outside of Milwaukee.
What is a waterspout?
According to NWS, there are two types of waterspouts. They are called fair weather waterspouts and tornadic waterspouts.
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"Tornadic waterspouts are tornadoes that form over water, or move from land to water," the NWS reports. "They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning."
The ones being seen in Lake Michigan appeared to be tornadic waterspouts.
"This is caused by cold air over a uniformly warm Lake Michigan," according to the NBC 5 Storm Team, which warns that "direct contact can be dangerous."
Fair weather waterspouts develop on the surface of the water and build upward, but are typically not associated with thunderstorms.
Should a waterspout move onshore, a tornado warning is issued, NWS reports.
