Currently, air quality advisories remain in effect for eastern Iowa through late Friday. Nearby areas may also see some smoke pollution. The Iowa Department of Natural Resources has warned that the impaired air quality could continue for several days.
Although it has not significantly affected air quality, smoke hanging at higher elevations remains widespread from Quebec and Ontario through the Midwest and Great Lakes to the Mid-Atlantic and Northeast coasts.
The smoke is circulated by a slow low-pressure system that loops between the Great Lakes and the Canadian Maritimes. Governing currents will be similar over the weekend until a high-pressure heat dome builds over eastern Canada, increasing the fire threat next week.
On Thursday, a plume of smoke from Canada produced a wide swath of Code Orange conditions, meaning unhealthy air for sensitive groups, from central North Dakota to northern Illinois.
Within that Code Orange area were pockets of Code Red conditions, signifying unhealthy conditions for most people. There were Code Red conditions in both Bismarck, ND, and Davenport, Iowa. After a day in code red Wednesday, air quality improved in southern Minnesota, including Minneapolis, on Thursday.
Since that day, key Code Red areas have been closer to the source of the fires in Quebec and Western Canada, where fires are also raging. Calgary has been seeing code red conditions since Thursday afternoon.
Calgary has seen several waves of smoke pollution due to record breaking fire season in north-central Alberta and British Columbia. The current smoking episode is the worst in about a month; in mid-May there were several code red days and even worse code purple conditions.
Another blob of Code Red conditions is underway in Quebec, with Code Orange levels near the international border with New York and New England. Monitoring stations northwest of Montreal and near Ottawa observed the code red levels on Friday.
The weekend smoke forecast
At least patchy areas of reduced visibility and smoke near ground level are likely in the coming days from the Midwest to the Mid-Atlantic. More patches of bad air could fall across the eastern Great Lakes and Ohio Valley.
By Saturday, a patch of unhealthy air could move from southern Quebec to northern New York and parts of New England, with the greatest concentration likely to remain near the international border.
It seems likely that smoke at higher altitudes will stick to similar areas where it has already enveloped sunlight. Much of eastern Canada and the northeastern quadrant of the United States could see milky skies over the weekend.
In Canada’s west, winds are expected to eventually shift to come more from the westerly, helping improve Calgary’s air quality. Significant air quality problems will likely continue in rural areas near the fires.
Fire threats are set to increase in eastern Canada over the weekend as a large dome of high-pressure heat takes over.
Much warmer-than-average conditions will expand across central Canada over the next few days before moving east over the next week. Some locations can end up as much as 20 or more degrees above average for several days, with the 80s and 90s a good bet from frigid Hudson Bay across eastern Canada and the northeastern United States.
Under the cloud-crushing heat dome, little rain is expected, although occasional lightning strikes and ineffective showers can appear in the heat.
Given the anticipation of light winds under the heat dome, smoke forecasting becomes increasingly difficult, but the general pattern could mean more activity from Quebec and Ontario moving east or southeast from its origin sooner back to the mid-Atlantic and northeast.
By the end of next week into next weekend, more consistent westerly winds up in eastern Canada may tend to keep the smoke outboard, but that’s good for the future and subject to a lot of change.
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