NOAA's Hazard Mapping System Fire and Smoke Product reports a large area of light smoke from North Dakota southward into northern Mexico, as shown in the top left image. This remnant smoke is from the various fires, discussed in past few days here in the Smog Blog, over northern Mexico, New Mexico and Colorado. The smoke yielded the high AOD retrieved by the MODIS sensor in NASA's Aqua satellite (top right image).
Out of the fires producing the remnant smoke aloft observed today in the satellite retrievals, the High Park fires in Colorado are impacting the air quality (Airnow animation below) in Fort Collins, Colorado as PM2.5 concentrations reached Code Orange levels (Unhealthy for Sensitive Groups). Cirrus clouds in the eastern coast of the United States hindered retrievals from satellites, but not for ELF. Lidar observations at UMBC shows the boundary layer extending up to 1.75 km, with cirrus clouds (8 to 13 km) advecting throughout the observations.