Smoke from large wildfires across the northwestern United States has been spreading eastward with the winds aloft, and covers a large portion of the Midwest. This satellite image from 6 pm Monday shows the smoke as milky gray shades (clouds appear as brighter white areas). This appears most prevalent over southern South Dakota, southward into western Oklahoma; a dense area of smoke aloft also appears over much of Indiana. A thinner smoke layer is indicated in between. While the smoke is present, sunrises and sunsets will appear more vivid than usual.