The term “polar vortex” has crept back into the news as a mass of cooler air threatens to descend on the Great Lakes and farther south. But experts are dismissing that talk as so much, uh, hot air.
If the long-range forecasts hold true — and they often don’t — it’ll be a bit cooler than normal and you won’t have to run the air conditioner. That’s about it.
“I would shy away from using the term polar vortex,” said Tim Axford, a National Weather Service meteorologist in Pittsburgh. “Over the past six months that term has been used a lot and gotten a lot of media buzz for something that happens quite often.”
What may happen is a dip in the air currents that will send cooler air from Canada, giving us a few days of high and low temperatures about 10 degrees below normal, Mr. Axford said.
The coolest day next week is forecast to be Wednesday, with a high of 74 degrees. The last two Julys had five days where the high was 74 or lower, according to weather service data.
Low temperatures are expected to fall into the mid-50s, not threatening the all-time record lows of 49 for Tuesday and 48 for Wednesday.
While it is not unusual to get a day or two of cooler weather in July, this pattern may persist a bit longer than normal, Mr. Axford said.
“People tend to get worked up into a frenzy about something that’s a week out,” he said. “There’s still some time for this to work itself out.”
“Poor man’s polar vortex to make shocking summer return in eastern U.S. next week,” blared a headline on The Washington Post’s website on Friday.
“Polar Vortex Part II,” headlined the CBS television station in Chicago.
“The pattern is reminiscent of a major polar plunge that occurred this past winter, which was referred to as the Polar Vortex,” said an AccuWeather meteorologist.
The warmer heads at The Weather Channel begged to differ.
Its headline: “Polar vortex in July? Not so fast.”
“While it’s a catchy term that gets a lot of attention, the polar vortex isn’t really to blame for the unusually cool weather that much of the nation is expected to see next week,” its meteorologists wrote.
“Here’s why: The polar vortex is a feature in the upper atmosphere over the Earth’s poles. In fact, there are two polar vortices — one over the North Pole and one over the South Pole as well.
“Both are rooted very high up in the layer of the atmosphere known as the stratosphere, which begins roughly about 25,000 feet to 45,000 feet above the Earth’s surface, but their circulations extend down into the troposphere, which is the layer of the atmosphere where we experience our weather. The portion of the circulation in the troposphere exhibits a much more wavy flow.
“Sometimes, the polar vortex does not shift, but rather pieces of the larger spin can break off and sweep toward southern Canada, helping to drive Arctic cold plunges into the U.S.
“The problem with the way this is often discussed in the media, however, is that the polar vortex exists in the stratosphere and not in the troposphere. So laying the blame for this anomalously cold outbreak of air on the polar vortex is incorrect — this air bubble is in an altitude much lower than where the polar vortex is located.”
More in the here and now, the National Weather Service expects a sunny day today with temperatures reaching the mid-80s. Sunday will be similarly warm with a chance of thunderstorms.
Jon Schmitz: firstname.lastname@example.org or 412-263-1868. Twitter: @pgtraffic.