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A dense shroud of haze from Canadian wildfire smoke is expected to gradually lessen over the next couple of days in Southwest and Southside Virginia, but it remains thick enough on this Thursday afternoon for breathing difficulties.
Visibility ranges commonly 10 miles or greater were cut down to only 2 to 5 miles this morning at many weather stations in Southwest and Southside Virginia by the thick smoke-induced haze.
Virginia Department of Environmental Quality measurements reported an Air Quality Index of over 160 in the Roanoke Valley area, where 150 or higher is considered unhealthy breathing for all people. Similar bad air numbers have not been recorded in more than 15 years.
Ozone haze from sunlight interacting with industrial, utility and automobile exhaust created frequent bad air quality days during the summers of the late 20th century and the first few years of the 21st century, before changing emissions and fuel standards and then the closing or conversion of many coal-fired power plants in the Ohio Valley, Appalachians and Mid-Atlantic regions reduced that problem dramatically.
The current air quality crisis is being imported from much farther way, as northerly wind flow from Canada has brought down smoke from rampant wildfires occurring in the northern parts of several provinces almost coast to coast. Smoke from Canadian wildfires has reached as far away as Italy.
Wind vectors aloft will gradually shift from north and northwest to more west and southwest over the next couple of days. The current plume of wildfire smoke affecting our region will disperse and eventually shift elsewhere, though some lingering haze may remain.
Somewhat hotter, more humid air will enter the region, with periodic chances of thunderstorms, circulating around intense high pressure bringing extreme heat to Texas and nearby states. At least in the next seven to 10 days, extreme heat is not expected to affect Virginia, though more lower 90s highs are anticipated to start July than we have seen so far in what has been a relatively cool June.
The fires in Canada will continue to burn in boreal forests, too large, numerous and remote to contain or fully extinguish by human means. Some experts expect the fires to continue until winter sets in.
That will mean we probably aren’t done with Canadian wildfire smoke this summer, as future cold fronts from Canada moving through the region may reintroduce northerly wind flow that would again bring the smoke southward.
Journalist Kevin Myatt has been writing about weather for 19 years. His weekly column is sponsored by Oakey’s, a family-run, locally-owned funeral home with locations throughout the Roanoke Valley.