Storms likely as steamy air mass approaches

Temperatures ranged as much as 21 degrees across the metro area Wednesday afternoon. While readings approached 80 degrees over the far southwest suburbs, lakefront temperatures dipped to around 60 as a lake breeze pushed onshore. Meanwhile, residents of the Plains experienced 90-degree heat, and rising humidity. The transition zone between these air masses will be a breeding ground for thunderstorm clusters. Storms are expected to focus on Chicago Thursday and Thursday night, bringing a threat of heavy rainfall to the city, and points north. The season’s hottest air to date is then forecast to sweep into the region.