Storm threat increases as holiday nears

Holidays never come with a guarantee of favorable weather. Consider the case of this year’s Fourth of July holiday period.
Chicago will find itself in a stormy transition zone between intensifying heat to the west and persistently cool temperatures to the east, overlaid by upper-level winds blowing from northwest to southeast.
That means any thunderstorms that might be triggered by daytime heating in the northern Plains will migrate southeast to the Chicago area—and computer models indicate that the Dakotas, Minnesota and eventually Wisconsin will be favored areas for storm development Tuesday and Wednesday.
By no means, however, are steady, all-day rains expected here. It is usually the nature of thunderstorms to be in and out of a given location rather quickly, and most hours during the holiday period will be rain free, despite the ongoing thunderstorm threat.
--By Richard Koeneman, WGN Weather Center Meteorologist