The last few days air quality in the Pacific Northwest has improved, as the fires discussed here are more than 50% contained. There is still smoke aloft over this region. This light smoke is the cause of the AOD retrieved from NASA MODIS sensor in Terra (top left image). The improvement is clearly observed in the top right image, which shows the daily PM2.5 values for the monitors near the Wenatchee, Salmon, and Sisters Forest Service forest fires. The plot is for the period of Sept. 1 to Oct. 17, 2012 (data courtesy of Airnowtech). During mid-September, wildfire PM2.5 concentrations reached values greater than 100 ug/m3. The latest values show concentrations no greater than 5 ug/m3.
Cloudy skies (seen at heights between 5-11 km) prevailed during today's lidar observations in Baltimore, as shown in the bottom image, with the boundary layer reaching heights up to 1.75 km.