A dense fog advisory continues for all of Southeast Michigan until 10 a.m. Monday. Fog is reducing visibility down to one-quarter mile or less in many communities.
The fog is leading to hazardous conditions in Metro Detroit. Drivers should allow extra time, slow down, maintain distance from other vehicles, and use headlights and fog lights.
While conditions will be better when the advisory lifts, patchy fog will linger into the afternoon.
Why is the fog so dense?
Snow that’s been on the ground for some time in Metro Detroit is now melting. While this is causing the ground to become very moist, warm and moist air has been flowing as well.
That moisture on the ground is creating some cooler conditions, the air is saturated, and there’s nowhere for all this moisture to go. So it’s really just stagnant and sitting above the ground at the surface creating these foggy conditions.
You have that warm air flowing over that cool, snowy ground. Which a lot of that snow has already melted at this point, but it is creating a situation of saturation and that dense fog.
You can watch the full explainer with visuals in the video above.
When will the advisory lift?
While that advisory lifts at 11 a.m. on Dec. 16, we will still have the potential of foggy conditions lasting into the afternoon hours. Now, we have seen some improvement in some locations, including in Downtown Detroit, where visibility was down to a mile.