Patchy dense fog across northwest portion of Chicago area early this Friday morning

Update 8:30AM CDT…

Visibility is improving rapidly and the Dense Fog Advisory will expire at 9AM CDT.

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With moist conditions due to scattered showers/thunderstorms Thursday, the spread between temperatures and dew-points has narrowed, resulting in patchy dense fog formation over a good portion of Chicago as well as the area to the northwest this Friday morning.

Visibility has dropped to a quarter-mile or less in some locations with poor visibility and dangerous driving conditions. Areas of lowest visibility at airport locations are shown on the visibility map below.

Be aware that these poor visibility conditions extend farther north into southern Wisconsin. Conditions should improve significantly by mid-morning. Actual Dense Fog Advisories are in effect until 9AM CDT for the gray-shaded counties on the second map below.

Map of Forecast Area