The large smoke emissions in the Northwest have reduced dramatically today. The MODIS fire counts are shown on the RGB of the Northern States below. The large fires in Idaho (Sheep, 47 kacres; McGuire, 75 kacres; Wesley, 15 kacres; Mustang, 338 kacres; and Halstead, 179 kacres) and Washington (Table Mountain, 38 kacres; Wenatchee Complex, 58 kacres; and Cascade Creek, 15 kacres) still encompass hundreds of thousands of acres of burned land and most are still less than 40% contained. In the midwest, fires in North Dakota and Saskatchewan are widespread and may indicate agricultural burning. Most of the fire radiative power for these fires are less than 20MW or small in size. The highest PM2.5 overnight was seen at the Oregon Sisters Forest Service station. The image on the right below shows the PM2.5 reaching 180 µg m-3.
Update: September 30, 2012
Idaho continues to be pretty quiet today and most of the smoke is from Washington's fires (left image). The right image shows one station with an Unhealthy reading at 16:00 UTC today but later in the afternoon, no stations are showing more than moderate PM levels. This must be quite a relief to those in the northwest.
The smoke in the prairies has died out today which looks like it was clearly of agricultural origin with farmers burning off the stubble in fields.
We won't be worrying about fires in the south and Texas is going to recover rapidly from their drought conditions. Parts of east Texas today got up to 10" of rain.