The first image below, courtesy NOAA HMS, shows the fire locations across the United States. The red dots correspond to active fires, and the grey areas are plumes. The largest plumes are continuously stretching from the Northwest to the Southeast regions of the country. A majority of the fires in the Northwest region and Canada are emitting large amounts of smoke which has been causing many health concerns as that smoke begins to reach the surface. There is also some fire activity in the Mississippi Valley and Plains region. Smoke of these northwest and Canadian fires has been sighted over UMBC and has been thinly aloft in the past few days in the Mid-Atlantic. The image below shows the CALIPSO lidar 532 Total Attenuated Backscatter image with an overpass over the Northeast region, emphasizing the PM 2.5 amounts and altitudes. There are large amounts of aerosols in the first few kilometers that are due to the wildfires in those coordinates. The large thick layer near 3 km centered around (50.00,-114.00) is right in the center of a Canadian plume. These plumes have been showing up along the mid-atlantic.
The first image below shows the UMBC ELF 532 Total attenuated backscatter lidar profile for 13:30-18:00 UTC. There are light layers aloft around 5 km for the beginning of the afternoon, which turn into a thick layer between 4 and 6 km that are stronger in the late afternoon (15:30 UTC). This plume has a strong gradient, indicating that it is a fairly strong layer aloft. The Hysplit Back-Trajectory below shows that the layers aloft in Baltimore, were most likely due to Pacific Northwest and Canadian fires and smoke.