Wildfire smoke is brewing in Canada, and some of that may make a return visit to Philly this summer

Almost the entire Northeastern United States was transformed into a Canadian smokehouse. It was so noxious that the Phillies experienced the first smoke-out in the team’s 140-year history.

The smoke, borne hundreds of miles on north winds from the wildfires in northern Ontario and Quebec, became so dense that people in the Philly region were calling 911 emergency dispatchers to report fires.

For three days beginning on June 6 last year, Philly’s air quality became about as bad as it ever gets around here, setting a record for fine-particulate pollution, officials reported. A walk outside was akin to inhaling two packs of Canadian woodland smoke. Smoky reinforcements arrived in the region later in the month.

While Canadian Prime Minister Justin Trudeau offered an apology (he was kidding, we think) when he visited Philly this week, he also warned, “We already started another wildfire season in Canada.”

As ominous as that might sound, that’s not quite accurate, said John R. Gyakum, an atmospheric scientist at McGill University in Montreal, who specializes in extreme-weather research: The 2023 season never quite ended.

“It was not much of a winter in a lot of the continent,” he said. “Many of these fires that were burning last summer lingered into the winter.” Some of these so-called zombie fires continued to smolder among the snowpacks, he added.

The long-range outlooks by Canada’s government meteorologists call for above-average wildfire conditions in much of the country in June, July, and August.

What are the prospects of a smoky encore over the skies of Philly? Meteorologists are understandably circumspect: They are far more confident that atmospheric chaos will fill the air across North America than they are about the smoke.

“I think we will see some in the middle of the summer,” said Paul Pastelok, the veteran long-range forecaster with AccuWeather Inc.

The company is calling for below-average wildfires in the United States, with drought conditions easing in the West. According to the interagency U.S. Drought monitor, more than half the West was in some state of drought last May, compared to about 40% with the latest weekly update.

However, AccuWeather says Canada’s wildfires could end up being above average, as the Canadian forecasters suggest, and that could affect air quality in some parts of the United States, as it already has.

That said, Pastelok says that Philly and the rest of the Northeast are very unlikely to experience anything like last June when Philly became a smoky version of San Francisco. Although it favors above-normal activity nationwide, the Canadian outlook has wildfire activity about normal in most of eastern Canada

For one thing, there’s less of it, especially in the unpopulated northeastern Canada woodlands that were the sources of last June’s torment. The world continues to warm and woods continue to burn, but the circumstances are very different.

That smoke, mixed down into lower levels of the atmosphere, was transported on persistent winds from the north — highly unusual in June, when prevailing winds are from the southwest.

Fires are common up that way, but last year’s were more extensive and intense than usual, said McGill’s Gyakum.

Along with warming, other factors may have included tropical storm remnants that took down trees up that way months earlier, and a beetle infestation that added more combustible wood to the pile, said Amy Freeze, a meteorologist with Fox Weather.

Fires in western Canada already have set off pollution alerts in the Upper Midwest. Recall that last year they clogged skies in some populated areas of North America into the fall. But they were so “off the charts” in 2023 that repeats of those intensities are unlikely, said Gyakum.

Predicting the path of “straight shot” smoke moving north-south from eastern Canada is one thing, said Pastelok, but if the prime smoke source region is going to be in the western part of the country, things get complicated. The smoke has to travel thousands of miles, typically six to seven miles in the atmosphere, sailing above irregular, air-disrupting terrain.

Because the pattern in June 2023 in the East was persistent, it was relatively easy to see the smoke coming. Predicting the onset of a given pattern and what it might do to the winds, however, is another matter, said Gyakum.

NOAA posts hourly smoke forecasts extending into the next day, but they aren’t always accurate.

“This is a metric that is extremely difficult to forecast for many reasons,” said Gyakum.

He likened predicting smoke forecasting to hurricane outlooks. Meteorologists can say, “We’re going to have an above-average number of hurricanes,” but “it’s just not at all clear that we’re going to have hurricanes that hit land.”

Pastelok said he wouldn’t mind a smoke-free summer.

Recalling last June, he said, “It got in the house. It was pretty nasty — and scary.”