Intense rainfall in northern and eastern Colorado brought widespread, destructive flooding in mid-September 2013. Local citizens reported as much as 18 inches (46 centimeters) of rain from September 9 to 15, with some of the heaviest accumulation along the front range of the Rocky Mountains. A break in the precipitation allowed the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite to acquire the top image of the floods on September 14. The lower image, taken by Terra MODIS on September 7, 2013, shows the region before the rains began.
The images were made from infrared light to increase the contrast between water and land. Water is typically black or dark blue in these images, but here the sediment-laden water and muddy ground are light blue. (In the true-color version, the muddy river blends with the brown landscape that surrounds it.) Irrigated farmland is bright green, while natural vegetation and bare ground are pale green and tan, respectively. Bright blue and white clouds still cover cities along the front of the Rocky Mountains, including Denver, Boulder, Loveland, and Fort Collins.
The South Platte River and its tributaries are swollen in the September 14 image. The South Platte peaked at 18.79 feet (5.73 meters) immediately east of Greeley on September 13 and was beginning to fall when the image was taken. Flood stage is 10 feet (3 meters).