On several occasions this summer, especially after the passage of a cold front, the sky has appeared hazy and dull. These conditions were particularly noticeable the past two days. These unusual sky conditions are associated with fires that have been burning for much of the summer in Saskatchewan. The fires are in a remote area, and from what I have read, allowed to burn with little human interaction. Therefore, with each cold frontal passage, the upper-level wind flow turns to the northwest allowing the smoke from these fires to move into North Dakota and northern Minnesota. Because of this, we may continue to have periods of a smoky sky until snow eventually puts these fires out.
In recent summers, fires from the northern Rockies would on occasion move into our area, but because much of the western part of the United States has been cooler and wetter than average this year, few fires have formed in those areas.