A vigorous cold front will be pushing across the Chicago area Saturday morning, introducing markedly cooler and drier air that promises a pleasant weekend. But thunderstorms will precede the front, arriving here Friday evening and ending Saturday morning. A few brief sprinkles are possible in the afternoon.
Heat bursts are an odd atmospheric event that can occur in thunderstorms. Most thunderstorms produce cooling gusts, but occasionally a parcel of air is pushed down from an elevation of 20,000 feet or higher to the surface, warming by compression all the way down.
At Glasgow, Montana, on Sept. 9, 1994, the temperature at 5:02 a.m. was 67 degrees. A heat burst from a nearby storm shot the temperature up to 93 by 5:17 a.m., tying the date’s record high. It was back to 68 degrees by 5:40 a.m.
