Hold any mouse button down as you move the cursor across the large topography image; the smaller inset window shows the corresponding 11:45 UTC GOES-8 fog/stratus product image. Surface reports are included on the fog/stratus product image, with the ceiling height [feet] plotted in bold cyan numbers. The concave eastern edge of the low stratus and fog (light gray enhancement) over southwestern Minnesota/northeastern South Dakota/southeastern North Dakota is due to the topography of that region (the Bemis Moraine escarpment). The easterly component of the surface winds created a subtle upslope flow situation, which played a role in the formation of stratus and fog in the nearly saturated air mass that was moving in from Minnesota.

For greater topographic detail, see the high resolution shaded relief maps of South Dakota and Minnesota (courtesy of Johns Hopkins University).