More winter weather is headed toward central Illinois.  Drivers are urged to be careful on the roads.  Authorities say drivers should plan ahead, give themselves plenty of time to get to their destinations, and take the necessary safety precautions while traveling on interstates and state roads.  Drifting snow will make if difficult to see.  Drivers are told to reduce their speed and leave space between themselves and the car in front of them.  They are urged to avoid abrupt stops and unnecessary lane changes.  Officials also tell them to always keep their gas tanks at least two-thirds full to prevent fuel from freezing.