Dense Fog Advisory covering much of the Chicago area until 9PM CST this Sunday evening
Update 9AM CST…
Dense fog with visibility down to a few feet in spots has spread north to the Interstate-90 corridor and a Dense Fog Advisory has been issued in effect until 9 PM CST this Sunday evening for much of the Chicago area (see grey-shaded area on the highlighted map). If traveling today, be alert for sudden changes in visibility due to the area-wide formation of dense fog. Current visibility in tenths of mile are depicted on the map below.
Visibility has dropped to a quarter mile or less in some spots south this Sunday morning with a Dense Fog Advisory (grey-shaded area on highlighted map) issued for areas well south of Interstate-80 into central Illinois. Overnight cooling has allowed temperatures and dew-points to come together in the middle 30s, causing the formation of fog at many locations. If you anticipate traveling south this morning, be aware that patchy dense fog has developed and visibility could drop to a quarter-mile or less at times the farther south you go (check map of visibility in tenths of a mile below).