"Hi Mom, God Bless U!" was written in the snow and could be seen from several hospital rooms, ABC7 Chicago reports.
A nurse reportedly saw four people writing in the snow around 1am Monday and snapped a photo. It is unclear who the intended recipient is.
Our sister station, WLS-TV, is trying to track down who wrote the message or who it was written for, and they are taking tips on the ABC 7 Chicago Facebook page.