Wildfires burning in the Pacific Northwest and northern/central Saskatchewan continue to produce a large area of moderately dense to very dense smoke moving east (top left image, NOAA Hazard Mapping System Fire and Smoke Product). Heavy residual smoke is observed stretching over a large section of northern/central Saskatchewan, Manitoba, and south through Quebec all the way into the Great Lakes region. This smoke is the cause of the high AOD values retrieved by NASA's MODIS sensor in the Aqua satellite (top right image).
The smoke is impacting the air quality in the Pacific Northwest leading to PM2.5 concentrations to increase to Moderate to Unhealthy to Sensitive Groups AQI levels (Code Yellow to Moderate), as shown in EPA's Airnow AQI animation. Also, Moderate PM2.5 AQI levels were reported in the eastern half of the United States. Lidar observations in Baltimore show the presence of clouds for the first five hours of observations around 5 km. During this time observable streaks or shaft of precipitation can be seen falling from the clouds. This phenomena is known as virga. Rain evaporates or sublimes before reaching the ground. After the clouds dissipated the growth of the boundary layer extended up 1.25 km, with occasional clouds capping it. ELF has been running since Monday in support of Maryland Department of the Environment.