Nearly a week after a powerful storm dumped heavy rain over Washington and Oregon, the region’s rivers still ran high and thick with muddy run-off. The storm caused floods and mudslides that closed roads, including Interstate 5, which connects Seattle and Portland, and cut off communities, reported the Associated Press. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying on NASA’s Terra satellite captured its first post-storm, cloud-free view of the soggy ground on the morning of December 8, top. Evidence of the floods can be seen in the murky color of the rivers.
The MODIS instrument flying on the Aqua satellite, which collects imagery in the early afternoon, captured the lower image on November 21. The forest-covered land is a deeper shade of green than on December 8 largely because the afternoon light is different. The photo-like November 21 image reveals that the rivers and ocean are typically a deep blue or blue green. On December 8, however, so much earth had entered the water that every visible river and stream is brown. The Chehalis and Columbia Rivers appear to be swollen as they absorb the floods draining from their basins. Each river sends a plume of sediment into the Pacific Ocean, turning the coastal waters tan and green. The vertical stripes in the ocean are artifacts from the satellite sensor, which captured the image at the edge of its field of view. The upper left corner of the December 8 image was made from a later overpass, by which time, a bank of clouds had moved over the water.
The snow-covered peaks of the Cascade Mountains line the right edge of the images. The range is dominated by massive volcanic peaks. Mount Rainier, Mount St. Helens, and Mount Adams are visible here.
Daily images of the northwestern United States are available from the MODIS Rapid Response System.
NASA images courtesy the MODIS Rapid Response Team at NASA GSFC.
- Terra - MODIS