As the hours ticked by Friday, it became clear that the face-melting temperatures forecast to envelop Chicago were as mythical as unicorns.
We had all been warned. Possible record-setting highs. A scorching heat index. A dehydrating start to the Fourth of July weekend.
Turns out weather can be a bit tricky. WGN meteorologist Tom Skilling explained late Friday that a batch of thunderstorms that were expected to move farther east of us came closer to the city and then hung out over the lake most of the day.
Those thunderstorms — “devilish things,” as Skilling called them — created what’s known as an “outflow boundary,” which basically means that they pushed cool air into the region, blocking out the hot air that was expected to infiltrate.
“Thunderstorms are famous for this,” said Skilling, who expected the warm air to creep in Friday night and bring 90-degree temperatures to the area Saturday. “This is one area that does get us at times, these thunderstorm outflow boundaries.”
To prove that the hot-weather prediction wasn’t all wrong, Skilling noted that by midafternoon it was 90 degrees in Rockford with a 100-degree heat index. But at the same time, Chicago was a cool 78 degrees.
“You don’t like busting a forecast,” Skilling said. “But in my line of work, it happens.”
