"Hi Mom, God Bless U!" was written in the snow and could be seen from several hospital rooms.
Surgical Intensive Care Nurse Angela Washek saw four people writing in the snow around 1 a.m. and snapped a picture from room 1155. It is unclear who the intended recipient is.
If you know who wrote the message or who it was written for, let us know on the ABC 7 Chicago Facebook page.