Take a look at the temperature contrast across the state of Missouri. Below is a surface observation map centered on Evansville, Indiana. All of the readings were taken at 2:00pm CT. (Click on the image to see a larger image.)
It is currently 62° in Cape Girardeau, Missouri. Where as in Columbia, Missouri it is 39° and in Sedalia, Missouri it is 33°. To say that we are on the warm side of the storm is an understatement.
Now you know why the National Weather Service is calling for snow around the St. Louis area. Below is the snowfall forecast from the St. Louis NWS through Sunday morning. (The forecast was made Friday morning.)