Summer’s death grip on the United States might loosen somewhat as we forge through the end of the month, as weather models are pointing to the possibility of the jet stream dragging down some of that cool Canadian air we all know and love (when it’s not January) just in time for the first week of August. Ahh.
Last year’s summer weather east of the Rockies is something I wish we could live over and over again, temperature-wise. Last August here at The Vane’s glass-enclosed nerd center in North Carolina, we had 13 days of highs below 80 degrees—three of which were in the 60s—when our average high usually sits in the mid- to upper-80s. We had our windows open a good number of days in June and July, too, and it was even cooler up north! Aside from small things like “unbearable heat” and “drought” and “fires” out west, there were very few complaints about the weather last year.
Fast forward to everyone complaining this year. Average high temperatures so far this summer—from June 1 through today—haven’t been quite as bad as they’ve been in other blistering years, but it’s still enough to warrant the use of air conditioning (amid the objections of Europeans, as with everything else we do). Much of the southern and Mid-Atlantic portions of the United States have seen warmer-than-average highs this summer, while cities in other areas like Boston or Chicago seeing high temperatures a degree or two below average this season.
Blame it on the jet stream.
If you’re a cool-weather person and can’t stand the thought of another month of heat and stifling humidity, you’re in luck. Even though it’s still more than a week out, weather models are trending toward the idea that we’ll see below-average temperatures across much of the northern half of the country beginning late next week.
According to the American global weather model—the GFS—a sharp trough in the jet stream will dip over the Pacific Northwest this weekend, bringing cooler-than-average temperatures to the region to start next week. As this trough (and eventually center of low pressure) straddles the border between the United States and Canada, it will trigger a realignment in the jet stream that shifts the ridge of high pressure that’s parked itself over the southern United States for the past couple of weeks. This ridge—responsible for the non-stop, choking heat plaguing the region—will scoot toward the Rockies and the southwest, allowing our old, familiar jet stream pattern to take hold.
The result will be a pattern we saw so many times this winter, with a large ridge hanging out over western North America while a trough digs through Canada and the United States east of the Rockies. This pattern will allow heat to build in the west and cool air to filter south from Canada in the east. Both the GFS and the much-vaunted European model show this scenario playing out, which lends credence to the idea that a significant portion of the country’s population is in for some open window weather.
How cool are we talking? Average! Most of these cooler temperatures are right around average for this time of the year, but we’re at the point where average is bearable in places like Minneapolis or Detroit.
Here’s some model guidance from the GFS model’s ensembles, which is generally good at showing trends in temperatures. Don’t focus so much on the exact numbers as the trend itself—it’s guidance, not a forecast.
New York City:
You can see that the cooling trend is more dramatic the farther north and farther away from the East Coast you are, with cities like Minneapolis and Detroit looking like they could come out on top of the world at the beginning of August.
Lots of things can change between now and then, but it seems like experts are hopping on the bandwagon. The Weather Channel’s 10- to 15-day forecast reflects the cooling trend, with highs hovering around 80°F in Minneapolis and Chicago after the first of the month.
It’s only in the north...
When I say “northern half of the country, I mean “northern half of the country.” Above is your forecast from The Weather Channel for Dallas over the next 15 days. The ridge is moving and a trough is coming, but cool Canadian air really only cares about the part of the country that doesn’t use the word “Canada” as an insult. Sorry! Better luck in September.