Over the past month, residents of the Red River Valley and Lakes Country have noticed the daytime skies occasionally having a hazy, smudgy brown color. From time to time the sunrises or sunsets have also been uniquely shaded, perhaps a muted tawny color or a bit more vibrant, reddish hue. Much of these optical variations are the result of large forest fires in Canada.
According to the Canadian Wildland Fire Information System, many of the recent, larger fires have been over the Northwest Territories, British Columbia, northern Alberta and northern Saskatchewan. Due to the winds in the middle and upper atmosphere, the smoke from these fires will occasionally be transported southeast into our region. Due to the fairly rapid movement of weather systems from northwest to southeast, the smoke does not linger; hence some days the sky is quite hazy while some days the sky is very clear.
Below are satellite images of smoke from the Canadian Fires as they move across the area. As a rule, due to the optical qualities of the smoke at these distances from the fires, the smoke plume does not show up very well in the visible satellite at certain times. However, for the hours just after sunrise the smoke is very prominent. Below is a visible satellite image from 815 am CDT Friday Aug1 2014.
Health Impacts: At this distance from the source of the fire, there are relatively few impacts expected. The plume is elevated well above the surface and quite dispersed when compared to the concentrations near the sources. However, for those interested the NWS does generate Air Quality Forecasts that include surface smoke concentration levels (in micrograms per cubic meter) as well as a Column-Integrated Smoke Concentration forecast.
The National Weather Service will continue to monitor these plumes as they occasionally move through the region. While very unlikely, atmospheric conditions could trap some of the smoke in higher concentrations near the surface. Should this occur, local NWS Offices would refer area residents to the Air Quality Forecasts and Public Health Sector for additional information.