An odd event was observed across the western portions of Upper Michigan Sunday afternoon as brown snow fell from the sky and covered the ground. The brown color can be attributed to dust originating across western Kansas and the panhandle of Oklahoma. When the system that brought snow to Upper Michigan Sunday was developing across the northern Great Plains on Saturday, strong southerly winds kicked up loose dust. This dust was carried northward by the strong winds across Nebraska and into the Dakotas. Once the dust reached the Dakotas, it became wrapped up in the developing storm circulation and was transported eastward on Sunday. When a patch of snow moved across far northern Wisconsin and western Upper Michigan Sunday afternoon, it deposited some of this dust across the area, leaving a fine brown coating on the snow.
The picture below shows satellite images taken at 4:30 and 9:00pm on Saturday, February 25th. On the left are "visible satellite" images, which are from the detection of visible sunlight reflected back toward the satellite. Once the sun has set, these images are unavailable, so other detection methods are required. The right images ("nighttime images") somewhat fix this issue. A combination of infrared (IR) energy that is emitted by the ground, clouds and, in this case, dust is used to create this image.
The dust appears as a murky gray color across western Kansas on the visible satellite at 4:30pm. By 9:00pm, a brighter patch of white on the nighttime image is evident across the Kansas/Nebraska border as the dust progresses northward.