The National Weather Service has issued a Severe Thunderstorm Watch for Chicago as well as many northern and western suburbs until 2AM Wednesday.
A line of severe thunderstorms has been raking across southern Wisconsin this evening, and is starting to drop south toward northern Illinois. The main threat from this line of storms will be damaging winds. Frequent lightning as well as torrential downpours are also expected. The storms and associated winds will begin to impact Chicago's northern suburbs between 9:30PM and 11PM.
Below: Counties included in Severe Thunderstorm Watch 616 until 2AM are shaded in pink.