The Philadelphia region has been getting a taste of October in September, and meteorologists say that is due in part to the historic wildfires out West.
Strong jet stream winds from the west-northwest in the upper atmosphere have exported smoke from the fires — blamed for killing at least 35 people — across the continent, and we are getting our share.
Ordinarily, with the center of fair-weather high pressure nearby, the skies should be profoundly blue; instead the smoke has bleached the color out of the skies and veiled them with a sun-dimming milky haze.
“You don’t know whether to call it cloudy or sunny," said Dave Bowers, a meteorologist with AccuWeather Inc, adding that the smoke has made it as far south as Kentucky and northern Virginia. The hourly observations from Philadelphia International Airport read “mostly cloudy.”
And the veil has been affecting temperatures.
The high Tuesday, 68, was 10 degrees the normal of 78 in Philadelphia. It had been forecast to climb into the low 70s. And the National Weather Service says the smoke might cost the region a couple of degrees on Thursday. The weather service’s forecast high has been trimmed back from the upper 70s to the mid 70s.
Of course, the wildfire fallout locally doesn’t compare to the horrors experienced by some residents of California, Washington, and Oregon, where unprecedented numbers of “megafires” — defined as those burning 100,000 acres or more — have raged.
The airborne plumes should have little or no effect on surface air quality around here, Robertson said, and sky conditions should improve this week.
The smoke might not disappear completely until a strong cold front presses southward from Canada and brooms away the haze, said Bowers.
That front, however, might lure some moisture from Sally, which is inundating the Gulf Coast, and showers are possible by Thursday night.