Southern Indiana was in the first flush of spring on March 1, 2011, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired the top image. Though the official start of spring was still nineteen days away, flooding and greening had already started. The lower image, taken on February 18, 2011 by the MODIS sensor on NASA’s Aqua satellite, shows late-winter conditions.
Over those 12 days, rivers swelled with melting snow and heavy rain. On February 27-28, heavy rain fell across much of the Midwest, including Indiana. The clouds cleared on March 1 to reveal widespread flooding throughout the upper Mississippi basin. In this image, the Wabash, Eel, and White Rivers are all swollen. The National Weather Service issued flood warnings for parts of the Wabash and Eel Rivers, and reported minor to moderate flooding on the other rivers in the image. Floods are visible on other rivers across the Midwest in the large image, which spans from Iowa to Ohio and from Canada to Kentucky.
If viewed in natural color, as if from an airplane, the muddy water and surrounding ground would blend together. To distinguish between water and earth, the satellite sensor uses both visible and infrared light. Water is black or dark blue in this image, and sediment-laden water or saturated ground is pale blue. Plant-covered land is green, and bare earth is tan-pink. Clouds are turquoise and white.
Not only did the changing season bring floods, but it also brought the beginning of the growing season. Land that had been bare in February was beginning to turn green in March. The bright fluorescent green spots are likely farmlands with cold-weather crops.
The floods were already subsiding by March 2, but they may be a preview of what is to come this spring. Many rivers in the Mississippi Basin flood annually, and the National Weather Service expected flooding through March as the winter’s above-normal snow melts and spring rains fall. Heavy rain and snow forecast for later this week in central Indiana could bring a fresh round of floods.