As the sun rose over Kentucky on Saturday morning, dense river valley fog was clearly evident on visible satellite imagery. The fog is identified by its stationary appearance compared to the moving cloud cover caused by showers over Indiana and Ohio. Another key to identifying the fog is how it takes the shape of the river basins in Kentucky. The fog was most prevalent over eastern Kentucky and can be seen on the satellite image loop below (6:45 AM EDT - 9:15 AM EDT). Notice how the fog begins to erode as we move into the daylight hours. This happens as the sun begins to heat up the earth's surface. The additional heat allows air to begin to rise, which helps to mix the fog out with drier air from aloft. You will also find webcam video from Mammoth Cave National Park showing the fog eroding this morning and comparisons of visible satellite images with actual river basins in Kentucky.
Below: Major Kentucky River Basins overlayed on visible satellite imagery to help compare with the river valley fog.
Below: Time lapse of images taken at Mammoth Cave National Park of the fog eroding out of the valley this morning.
Below: The names and locations of major river basins in Kentucky.