Philly is under an air-quality alert Friday, but weekend looks good for mothers and concerts

Midsummer was very much in the Philadelphia air Friday — and not only in terms of temperatures topping out in the July-like mid-80s.

The Delaware Valley Regional Planning Commission declared the season’s first “code orange” air quality alert for Philly and its neighboring Pennsylvania counties, primarily for an overabundance of a summer staple, ground-level ozone, said DVRPC air-quality specialist Sean Greene.

High ozone levels can be dangerous for “sensitive groups,” including people with background respiratory and heart conditions, health officials said, and it’s possible that Friday’s alert may be related to all that Canadian wildfire smoke.

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However, the air was showing signs of improving during the day Friday, said Amanda Lee, a meteorologist at the National Weather Service Office in Mount Holly.

What’s more, she said, by Mother’s Day the weather should be quite splendid, and those attending the Taylor Swift concerts on Friday, Saturday, and Sunday nights should have nothing to fear from the skies.

The code orange ozone levels likely were related to an “inversion” Friday morning, Lee said. Warm air rises over cooler air, but an inversion occurs when the air bumps into a warmer layer and gets trapped near the surface.

Meanwhile the ozone brewed by the sun and the heat and the likes of auto exhaust ripen in the lower levels of the atmosphere.

Code orange is a step below “code red,” in which the air would be potentially harmful for everyone. The ozone season in Philly typically extends from May to September.

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Those inversion conditions were easing during the day Friday, Lee said, although the code orange alert remained in effect.

The wildfire smoke from northwestern Canada may have made at least a minor contribution to Friday’s air-quality issues. The Pennsylvania Department of Environmental Protection had advised that some of that smoky material might “mix down” around here on Friday.

The early-season fires, which had led to more than 25,000 reported evacuations, fed plumes of smoke into the upper-level west-to-east jet-stream winds, which carried them across the eastern United States.

The winter in that part of Canada, dry and mild, was the reverse of the profoundly wet and snowy winter in the Sierras, thousands of miles to the south, said Brandon Buckingham, a smoke-forecasting specialist with AccuWeather Inc. Thus it was primed for wildfire season.

Conversely, California’s fire season may get off to a slower start, he said.

The Canadian smoke has been evident over the Philly region the last few days, but at 15,000 to 20,000 feet, it likely was too high to have much effect on air quality here, Buckingham said.

He added that on Friday it evidently had been routed from the air over Philadelphia, although conditions favored more fires next week, and perhaps fresh rounds of smoke.

Some rain showers may fill the air during the day Saturday, when temperatures will be several degrees cooler than Friday, said Lee.

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They will be set off by an approaching front that should be long gone by the time Swift takes the stage on the second night of her Eras Tour concert at the Linc.

The front will also bring a Mother’s Day gift, a gorgeously sunny Sunday with highs in the 70s, and one more rain-free concert.