The Storm Prediction Center has placed portions of central Illinois, including Champaign-Urbana, in a 'Marginal Risk' for strong to severe thunderstorms this afternoon.
For C-U specifically...
When: Between 1 PM and 4 PM
What: A line of rain storms, with the potential for embedded strong to severe storms capable of producing primarily gusty winds, though one or two very brief tornadoes somewhere in eastern Illinois is not impossible.
On strong southerly winds in advance of the storm system, we'll warm back to around 70 degrees by the lunch hour here in Champaign-Urbana. As a cold front rapidly approaches from the west, a line of rain and thunderstorms will develop along it around the lunch hour. This line should reach C-U between 1 PM and 4 PM, again, producing perhaps some gusty winds as it moves through. After that, as we head into the evening we'll be cooling off rapidly as winds shift out of the northwest - dropping into the 30s overnight, and only topping out around 40 degrees on Saturday afternoon.