It will feel warm in Chicago on Tuesday. And then, suddenly, it won’t.
A “pneumonia front” is set to blow over the city Tuesday evening. It will drop temperatures over 20 degrees along the lakefront “in a matter of minutes,” according to the National Weather Service.
“It may be shorts weather this afternoon with temps near 80, but don’t let your guard down,” the weather service wrote in a tweet.
The cold front is expected to sweep in from Lake Michigan to hit northeastern Illinois between 5 and 8 p.m., according to the weather service.
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Temperature drops are expected to be less dramatic farther inland.
The weather pattern’s catchy name describes a “lake-enhanced cold front,” weather service meteorologist Ricky Castro said.
As cold fronts come down across the lake, they tend to accelerate over the lake’s still-cold waters, Castro said. The fast-moving air leads to quick drops in temperatures and winds, he said.
Areas around 80 degrees Tuesday afternoon will likely drop into the 50s in an hour or two, Castro said.
“It’ll bring an abrupt and unwelcome end to a nice, warm day,” he added.
Temperatures are expected to drop into the high 40s i Tuesday night. Onshore winds are forecast Wednesday, meaning temperatures will again be cooler by the lake. . Highs are forecast in the upper 50s.
Chicago is expected to warm up Thursday and Friday, with forecast highs near 70 degrees. Another cold front is expected to nudge temperatures down into the weekend. Highs are forecast in the mid 60s on Saturday, Sunday and Monday, according to the weather service.
“It is going to be generally colder near the lake for this upcoming stretch, but nothing too cold for this time of year,” Castro said.
There is a chance of rain Friday, and smoke from a wildfire in Alberta is expected to pass over Chicago on Tuesday evening and could persist intermittently through Friday, Castro said.
The smoke is expected to pass high above the city, likely at levels that wouldn’t substantially affect air quality, but could make skies “milky” and add a reddish-pink tint at sunset, according to the weather service.