Over the next 24 hours Chicago will play host to three heavyweight jazz and improvised-music concerts. Unfortunately it’ll be hard to see them all; one’s already sold out, and another happens during the lunch hour tomorrow. The ICP Orchestra, who I wrote about in this week’s paper, play a free concert tonight at the Chicago Cultural Center; sadly, pianist and cofounder Misha Mengelberg won’t be present (he returned home to Amsterdam this past week, suffering from fatigue), but the other nine musicians can be counted on to deliver a knockout performance. If you’re not familiar with these Dutch masters, then skip to the bottom of the post for the riotous video to “Steigerpijp,” one of many great tunes from last year’s ICP Orchestra (ICP). The other two shows? The Brad Mehldau Trio at SPACE in Evanston later tonight and the Ullmann/Swell 4 tomorrow afternoon at the Chicago Cultural Center. More on them after the jump.