Patchy dense fog with visibility of 1/2 mile or less will occur
early this morning across portions of northwest Illinois. Expect
to encounter sharply reduced visibility and rapid changes in
visibility when driving in and out of this patchy dense fog. The
foggy conditions should improve after 4 AM as west winds increase
and some high clouds move in from the northwest. Until then
motorists are advised to leave extra travel time and to reduce
speed, use low beams, and increase following distance when driving
in dense fog.