This animation of AWIPS GOES-12 fog/stratus product images shows a signal (yellow to orange enhancement) indicating that narrow fingers of river valley fog were forming during the pre-dawn hours across parts of southwestern Wisconsin, southeastern Minnesota, and northeastern Iowa on 29 July 2007. Although there is a certain amount of noise inherent in the GOES fog/stratus product (as seen by the widespread "false alarm" yellow pixels across the region), areas where fog/stratus is becoming thicker and increasing in areal coverage tend to show up as more continuous clusters of yellow to orange enhanced pixels.